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SnapRAID Log Format(1) General Commands Manual SnapRAID Log Format(1)

NAME

snapraid_log - SnapRAID Log Format

DESCRIPTION

This document describes the structured log tags output by SnapRAID, which are designed to be used by tools monitoring the SnapRAID processing state. The tags provide information in an easy-to-parse format, ideal for automation and integration.

To capture these structured log tags, you must use the `--log` option with SnapRAID.

You can direct the output to a specific file, or force the output to the standard output or standard error using the special arguments `>&1` or `>&2`. Note that these arguments often need to be quoted on the command line to prevent the shell from interpreting them.

Example:

snapraid status --log ">&2"

The output tags strictly adhere to the following format:

NAME:VALUE:VALUE:VALUE...<EOL>

This is the primary tag identifier, always a lowercase string without spaces (e.g., `summary`, `block`).
Following the `NAME`, these can be additional sub-identifiers, descriptive names (like a disk name), or numeric/string data values. They are separated by a colon `:`.
<EOL>
Each tag is terminated by an end-of-line character.

This document provides a summary of the tags generated by SnapRAID. For the most detailed and up-to-date information regarding the meaning and context of the values, it is recommended to check the source code´s `log_tag()` statements.

When a path is output, it is always escaped using a backslash (\) as the escape character.

The following characters are escaped into sequences:

The colon is escaped to \d.

The newline is escaped to \n.

The carriage return is escaped to \r.

The backslash is escaped to \\.

Some tags are output only when the `--gui` or `--gui-verbose` option is used. They provide extra verbose state and runtime progress only useful for a GUI interface.

Integer values are marked as `uint` when they are unsigned and as `int` when they are signed. However, for practical purposes you can treat all of them as signed integers. All integer values should be assumed to be 64 bits wide, regardless of the signed/unsigned marker. Floating point values are marked as `float`.

CONFIGURATION TAGS

These tags report the memory usage and global configuration.

Configuration file loaded (escaped).
Operating without a configuration file.
The configured block size in bytes (uint).
The data disks as defined in the configuration file.

<disk_name> The assigned name of the disk.

<dir> The directory entry point of the disk.

<uuid> The UUID of the filesystem containing the dir.

The RAID mode used. One of `par1`, `par2`, `par3`, `par4`, `par5`, `par6` or `parz`. The number indicates the maximum number of simultaneous disk failures the array can withstand.
<parity_level>[/<split_index>]:<path>:<uuid>
The parity files as defined in the configuration file.

<parity_level>[/<split_index>] One of `parity`, `2-parity`, In case of split parity, the parity name is followed by `/N` to indicate the split index, where N starts from 0. The `/0` is always omitted.

<path> The path (escaped).

<uuid> The UUID of the filesystem containing the path.

The filesystem information of the specified data disk.

<size> The size of the data disk (uint).

<free_size> The free size in the data disk (uint).

The filesystem information of the specified parity disk. In case of multiple splits this is the sum of the sizes of all splits.

<size> The size of the parity disk (uint).

<free_size> The free size in the parity disk (uint).

The filesystem information of the specified data disk.

<size> The size of the data disk (uint).

<free_size> The free size in the data disk (uint).

<type> The filesystem type. A string like `ext4`, `ntfs`.

<label> The label associated to the filesystem.

The filesystem information of the specified parity split.

<size> The size of the parity disk (uint).

<free_size> The free size in the parity disk (uint).

<type> The filesystem type. A string like `ext4`, `ntfs`.

<label> The label associated to the filesystem.

The configured dir to the pool mount point (escaped). This is the optional mount point for the ´pool´ feature.
The configured dir to the pool mount point (escaped). This is the optional mount point for the ´share´ feature.
If the autosave feature is enabled, and after how many bytes (uint). This specifies the interval for content file saving.
All the active filters with their patterns. These patterns exclude specific files or directories from the SnapRAID array.
If the no-hidden filter is enabled, meaning hidden files/directories (starting with ´.´) are excluded from the array.

CONTENT TAGS

These tags report the information stored in the content file.

The absolute path to a content file being used (escaped). Content files store the metadata (like file hashes and timestamps) for the array.
The absolute path to a content file being written (escaped). You will see multiple writes as the content file is saved in multiple copies.
The size of the data disk as stored in the content file.

<disk_name> Name of the data disk.

<size> The size of the data disk (uint).

<free_size> The free size in the data disk (uint).

The size of the parity disk as stored in the content file. In case of multiple splits this is the sum of the sizes of all splits.

<parity_level> Name of the parity.

<size> The total size of the parity disk (uint).

<free_size> The free size in the parity disk (uint).

The data disk info as stored in the content file.

<disk_name> Name of the data disk.

<uuid> The UUID of the disk filesystem as stored in the content file.

The parity split info as stored in the content file.

<parity_level>[/<split_index>] One of `parity`, `2-parity`, In case of split parity, the parity name is followed by `/N` to indicate the split index, where N starts from 0. The `/0` is always omitted.

<uuid> The UUID of the disk containing the path.

<path> The path of the parity file (escaped).

<size> The size of the parity file (uint).

The counters in the content file. The `kind` is one of the following:

file The count of files.

hardlink The counter of hardlinks.

symlink The counter of symlinks.

dir_empty The counter of empty directories.

block_bad The counter of bad blocks. Bad blocks indicate data or parity corruption.

block_rehash The counter of blocks needing a rehash, usually due to hash algorithm change.

block_unscrubbed The counter of blocks that are unscrubbed (just synced), meaning they have never been verified since their first sync.

block_unsynced The counter of blocks that are unsynced (need a sync), meaning their parity data is out of date.

block The total counter of blocks.

Total number of info records listed with `bucket`.
Total number of info blocks listed with `bucket`. This is the sum of all the counters listed.
The info records.

<time> Unix timestamp of the scrub/sync.

<count_scrubbed> Number of blocks scrubbed at this timestamp.

<count_new> Number of blocks that were synced at this timestamp and haven´t been scrubbed yet.

DIAGNOSTICS TAGS

The version of SnapRAID run.
The current time in the unix format (uint), representing seconds since the epoch.
The current time in human format.
The command run. One of `sync`, `scrub`, `check`, `fix`, `status`, ...
All the arguments of the executable command. The 0 one is the executable run.
The total memory currently used by the application in bytes (uint).
Size of the internal `snapraid_block` structure in bytes (uint).
Size of the internal `snapraid_extent` structure in bytes (uint).
Size of the internal `snapraid_file` structure in bytes (uint).
Size of the internal `snapraid_link` structure in bytes (uint).
Size of the internal `snapraid_dir` structure in bytes (uint).

SCAN TAGS

These tags report detected differences between the filesystem and the content file. They are output for every discovered change.

A file, link, or directory is equal (unchanged). No action is required for this item. Only produced when `--gui-verbose` option is used.

<disk_name> Name of the data disk.

<path> Path to the file/link relative to the disk mount (escaped).

A new file or link was found that is not in the content file. This item will be added to the array in a `sync`.
A file or link has been removed from the filesystem since the last sync.
A file or link has been updated (size, timestamp, or link target changed). This item will have its content data blocks re-hashed in a `sync`.
A file was moved to a different directory on the same disk. This is an efficient operation that only updates the path metadata without rehashing blocks.

<old_path> The old path to the file (escaped).

<new_path> The new path to the file (escaped).

A new file was found to be a copy of a file on the same or any other disk. This is detected by matching the file name, size, and timestamp, and is an efficient operation that avoids rehashing all blocks.

<source_disk> The original file´s disk.

<source_path> The original file´s location (escaped).

Like `copy`, but the original file has disappeared. The difference between `move` and `relocate` on the same disk is that `move` is only used if the inode remains the same.
A file´s inode has changed but not its directory, name, timestamp and size, which suggests the file may be restored from backup. The file won´t be re-hashed in `sync` as its precomputed hash is assumed to be correct.

These tags provide a final count of all detected changes.

Total number of files and links whose metadata and data match the current parity (uint).
Total number of brand new files and links not present in the last sync (uint).
Total number of files and links that existed in the last sync but are now missing (uint).
Total number of existing files where the timestamp or size has changed (uint).
Total number of files relocated to a new path or renamed but retaining the same inode (uint).
Total number of new files created by copying an existing protected file to a new path (uint).
Total number of new files created by relocating an existing protected file to a new path (uint).
Total number of new files matching a parity entry by name/time/size but with a new inode (uint).
Logs the overall exit status of the command. The `status` is one of the following:

equal Indicates that no differences were found. The array is already synchronized.

diff Indicates that differences were found. The array needs a `sync` operation.

unsynced The array has an interrupted sync. The array needs another `sync` operation.

GENERAL PROGRESS AND EXECUTION TAGS

These tags are used to report the runtime processing of the commands `sync`, `scrub`, `check` and `fix`. Only produced when `--gui` option is used.

A tag indicating the start of the command execution.

<blockbegin> Starting block index (uint).

<blockend> Ending block index + 1 (uint).

<count> Number of blocks to process. It may be less than <blockend> - <blockbegin> + 1 if some blocks are going to be skipped (uint).

A zero-argument tag indicating the end of the command execution.
Detailed progress information during command execution.

<blockidx> Current block index position processed (uint).

<blockdone> Number of blocks processed (uint).

<sizedone> Current size processed (uint).

<perc> Completion percentage (uint).

<eta> Estimated time to completion in seconds. Empty if not available (uint).

<speed_mbs> Data processing speed in MB/s. Empty if not available (uint).

<cpu> CPU usage percentage. Empty if not available (uint).

<elapsed> Elapsed time in seconds (uint).

<temp> Current max temperature of the disks. Empty if not available (uint).

<steady_temp> Expected steady temperature of the disks. Empty if not available (uint).

A user interruption (e.g., Ctrl+C) was signaled. The process is gracefully aborting.

<blockidx> Current block index position (uint).

<msg> Text message exactly as it´s printed on screen.

Messages printed to the screen.

<level> One of `fatal`, `fatal_hardware`, `error`, `error_hardware`, `expected`, `status`, `progress` or `verbose`.

fatal, fatal_hardware A fatal error occurred. Program will abort after this message. The `hardware` one means that the problem was caused by a hardware failure, like an Input/Output error or a silent data error.

error, error_hardware A generic error condition that doesn´t prevent the program to continue. The `hardware` one means that the problem was caused by a hardware failure, like an Input/Output error or a silent data error.

expected An expected error condition. At present it happens only when using the `-m` option with files expected missing.

status A status message, usually providing context or a summary.

progress A progress message, often part of an ongoing operation.

verbose A verbose informative message, only shown in verbose mode.

<msg> Text message exactly as it´s printed on screen.

THERMAL TAGS

The following tags are produced by the thermal monitoring functions when SnapRAID is processing, typically during operations that involve disk access.

Logs a temperature reading found in the system using the Linux /sys/class/hwmon interface. Only present in Linux.

<hwmon_dir> The hwmon directory name (e.g., hwmon0).

<name> The name of the hwmon device (e.g., k10temp).

<temp_file> The temperature file name (e.g., temp1_input).

<label> The label associated with the temperature sensor (e.g., Tdie).

<temp> The temperature reading in degrees Celsius.

Reports a temperature reading that is a candidate for the ambient temperature, used in the heating model calculation.

<temp> The candidate temperature in degrees Celsius.

Logs a temperature reading from a connected disk that is being considered as a candidate for determining the ambient system temperature.

<temp> The current temperature read from the disk (uint, degrees Celsius).

Logs the final ambient system temperature calculated. This value is the lowest valid temperature observed among all candidates, representing the room temperature.

<temp> The calculated ambient temperature in degrees Celsius.

Logs the most recent temperature reading for a specific disk device.

<disk_name>[/<split_index>] The configured name of the disk. In case of split parity, the parity name is followed by `/N` to indicate the split index, where N starts from 0. The `/0` is always omitted.

<device> The unique device ID (uint).

<temp> The current temperature read from the disk in degrees Celsius.

Logs the highest temperature observed among all monitored disks in the current measurement cycle. This is used for thermal throttling.

<temp> The highest temperature observed in degrees Celsius.

Logs the entire history of temperature data points collected so far for a specific disk, used for fitting the heating model. Only monotone increasing temperatures are included in the history.

<device> The unique device ID (uint).

<count> The total number of collected data points (uint).

<data_points> A comma-separated list of temperature/time pairs. Each pair is formatted as <temp>/<time_offset>.

<temp> Temperature reading in degrees Celsius.

<time_offset> Time offset from the start of the thermal monitoring (uint, seconds).

Logs the estimated parameters for the exponential heating model (fit using least squares) and associated quality metrics for a specific disk. The model is: T(t) = T_steady - (T_steady - T_0) e^(-kt), where T_0 is the initial temperature.

<device> The unique device ID (uint).

<k_heat> The heating rate constant, k (float).

<t_ambient> The ambient temperature, T_ambient (float).

<t_steady> The estimated steady-state temperature, T_steady (float), which is the maximum expected temperature of the disk.

<rmse> Root Mean Square Error of the fit (float).

<r_squared> Coefficient of determination (R^2) of the fit (float).

<max_error> Maximum absolute error of the fit (float).

Indicates that the thermal alarm limit has been reached, and the process is initiating a disk spindown to begin the cooldown procedure, preventing overheating.
Indicates the duration of the cooldown waiting period after spindown.

<sleep_time> The total time the system will wait for cooldown (uint, seconds).

Indicates that the cooldown period is complete, and the disks are being spun back up to resume the operation.

COMMAND STATUS TAGS

This section describes the tags output with the `status` command.

Summary Tags

These tags provide general information about the array configuration and overall state.

The size of a block in bytes. This is the unit of parity protection.
The total number of blocks allocated for all parity levels combined.
Total blocks available for a specific parity level (e.g., `parity`, `2-parity`).
Free blocks available for a specific parity level.
The minimum number of free blocks across all parity levels. This determines the maximum size of data that can be added.
Total number of files in the array.
Total number of data blocks used by files.
Total number of fragmented files, meaning files whose blocks are not contiguous.
Total number of excess fragments (one less than the total fragments). This is a measure of data fragmentation overhead.
Total number of files with a zero sub-second timestamp. This can occur on certain filesystems and may affect change detection.
Total size of all files in bytes.
Total size of allocated parity blocks in bytes.
Maximum possible parity size (allocated + min free) in bytes. This is the effective maximum protection size.
The current hash algorithm in use (e.g., `sha256`).
The previous hash algorithm used, if a rehash is in progress.
The best hash algorithm for optimal performance based on system capabilities.
Total wasted space (space on data disks exceeding parity capacity) in bytes.
Total used space by data files in bytes.
Total free space (usable by data) in bytes, limited by parity capacity.
Overall array use percentage.
Days ago the oldest block was last scrubbed.
Days ago the median block was last scrubbed.
Days ago the newest block was last scrubbed.
Logs the overall exit status of the command. The `status` is one of the following:

ok No issues. The array is fully synchronized and healthy.

bad The array has some blocks marked as bad. The array needs a `-e fix` and and a `-p bad scrub` operation.

unsynced The array has an interrupted sync. The array needs another `sync` operation.

Per-Disk Tags

These tags provide statistics for individual data disks. <name> is the disk name.

Number of files on the disk.
Number of blocks used by files on the disk.
Number of fragmented files on the disk.
Number of excess fragments on the disk.
Number of files with zero sub-second timestamp on the disk.
Total size of files on the disk in bytes.
Highest block index used on the disk + 1.
Total blocks on the disk (physical size).
Free blocks on the disk.
Total blocks by disk space (used + free blocks), representing the physical limit of the disk.
Total blocks limited by parity space (parity size + min parity free blocks). This is the logical limit imposed by the parity files.
Maximum usable blocks (minimum of `..._by_space` and `..._by_parity`).
Wasted space on the disk in bytes (positive if disk is larger than usable parity space).
Used space on the disk in bytes.
Free usable space on the disk in bytes, limited by `disk_block_max`.
Disk use percentage relative to `disk_block_max`.

File Timestamp Tags

These tags list files with zero sub-second timestamps.

Lists files that have a zero sub-second timestamp. Up to 50 are logged per disk.

Scrub Graph Tags

These tags provide a simple graph data of the past scrub and sync operations.

Dimensions of the scrub history graph obtained from the `content_info:bucket` records. This provides the boundary for the precomputed graph data available in the `scrub_graph_bar` tags.

<max_columns> The number of columns in the graph.

<max_height> The maximum height (peak count) of blocks found in any column (the highest sum of scrubbed and new blocks).

Data for a column of the scrub history graph. Each column represents a time period.

<index> Column index. From 0 to max_columns - 1.

<days_ago> Days ago for this column´s time range.

<scrubbed> Count of scrubbed blocks in that day range.

<new> Count of newly synced (unscrubbed) blocks in that day range.

COMMAND SYNC/SCRUB TAGS

Tags specific for the `sync` and `scrub` commands. Also the error tags are possible.

Summary Tags

These tags provide summary statistics at the end of the command.

Logs the total count of file-related errors that caused a block to be skipped during the hashing phase. These are often due to file changes (missing, size/time change) during the sync operation. This happens only in `sync`.

<count> Total number of file errors (uint).

Logs the total count of file-related errors encountered during the process (e.g., missing files, file attribute changes).

<count> The total number of file errors encountered (uint).

Logs the total count of input/output errors encountered on data or parity disks.

<count> The total number of I/O errors encountered (uint).

Logs the total count of `silent data errors` (data blocks not matching their expected hash) encountered during the sync process.

<count> The total number of silent data errors encountered (uint).

Logs the overall exit status of the command. The `status` is one of the following:

ok No issues. The array is fully synchronized and healthy.

warning Some files were skipped due to likely intentional modifications. No hardware risk.

error Critical failure. Indicates serious issues like I/O failures or silent data corruption. Requires immediate hardware or filesystem inspection.

COMMAND CHECK/FIX TAGS

Tags specific for the `check` and `fix` commands. For `audit` mode, it´s inteded `check` with the `--audit-only` option. Also the error tags are possible.

Fixed/Recovered Tags

These tags log successful repairs during fix operations.

Indicates that a file was successfully fixed using parity data.

<block_pos> The block position being processed (uint).

<disk_name> The name of the disk.

<file_path> The file path relative to disk root (escaped).

<msg> A descriptive message indicating the nature of the fix (e.g., `Fixed size`, `Fixed data error at position...`).

Indicates that corrupted parity data was successfully recomputed and written.

<block_pos> The block position being processed (uint).

<parity> The name of the parity level (e.g., `parity`, `2-parity`).

<msg> A descriptive message indicating the nature of the fix (e.g., `Fixed data error`).

Logs successful recreation of a missing or corrupted empty file.

<disk_name> The name of the disk.

<file_path> The file path relative to disk root (escaped).

<msg> A descriptive message indicating the nature of the fix (e.g., `Fixed empty file`).

Logs successful recreation of a hard link during fix operation.

<disk_name> The name of the disk.

<link_path> The hard link path relative to disk root (escaped).

<msg> A descriptive message indicating the nature of the fix (e.g., `Fixed hardlink error`).

Logs successful recreation of a symbolic link during fix operation.

<disk_name> The name of the disk.

<link_path> The symlink path relative to disk root (escaped).

<msg> A descriptive message indicating the nature of the fix (e.g., `Fixed symlink error`).

Logs successful recreation of a missing directory during fix operation.

<disk_name> The name of the disk.

<dir_path> The directory path relative to disk root (escaped).

<msg> A descriptive message indicating the nature of the fix (e.g., `Fixed dir error`).

Unrecoverable Error Tags

These tags log errors that could not be recovered.

Indicates that a block error could not be fixed due to insufficient parity or other recovery limitations.

<block_pos> The block position being processed (uint).

<disk_name> The name of the disk.

<file_path> The file path relative to disk root (escaped).

<msg> A descriptive message indicating the nature of the problem (e.g., `Unrecoverable error at position <file_pos>`, `Unrecoverable unsynced error at position <file_pos>`).

Logs that the modification time was not set on a recovered file to avoid inode collision with another file.

<disk_name> The name of the disk.

<file_path> The file path relative to disk root (escaped).

<collision_path> The path of the colliding file (escaped).

<msg> A descriptive message indicating the nature of the problem (e.g., `Not setting modification time to avoid inode collision`).

File Status Tags

These tags log the final status of files after processing.

Indicates that a file has unrecoverable errors and was renamed to `.unrecoverable` (fix) or cannot be recovered (check).

<disk_name> The name of the disk.

<file_path> The file path relative to disk root (escaped).

Logs that a file was successfully recovered during fix operation.

<disk_name> The name of the disk.

<file_path> The file path relative to disk root (escaped).

Logs that a file has errors but could be recovered with a `fix` (check).

<disk_name> The name of the disk.

<file_path> The file path relative to disk root (escaped).

Indicates that a file passed all checks successfully (verbose).

<disk_name> The name of the disk.

<file_path> The file path relative to disk root (escaped).

Summary Tags

These tags provide summary statistics at the end of the command.

Logs the total count of file-related errors encountered during the process (e.g., missing files, file attribute changes).

<count> The total number of file errors encountered (uint).

Logs the total count of input/output errors encountered on data or parity disks.

<count> The total number of I/O errors encountered (uint).

Logs the total count of `silent data errors` (data blocks not matching their expected hash) encountered during the sync process.

<count> The total number of silent data errors encountered (uint).

Logs the total number of errors successfully recovered (fix).

<recovered_count> Number of recovered errors (uint).

Logs the total number of errors that can be recovered (check).

<recoverable_count> Number of recoverable errors (uint).

Logs the total number of unrecoverable errors (fix/check).

<unrecoverable_count> Number of unrecoverable errors (uint).

Logs the overall exit status of the command. The `status` is one of the following:

ok Indicates that the operation completed with no errors (audit).

warning Some files were different than expected, likely caused by intentional modification of the files. No hardware risk (audit).

error Critical failure. Indicates serious issues like I/O failures or silent data corruption. Requires immediate hardware or filesystem inspection (audit).

recovered Indicates that the operation completed with all errors successfully recovered (fix).

recoverable Indicates that errors were found but are all recoverable (check).

unrecoverable Indicates that unrecoverable errors were found (check/fix).

COMMAND LIST TAGS

This section describes the tags output with the `list` command.

List Tags

These tags log details about individual files and links processed during the listing operation.

Logs details for a regular file found on a disk.

<disk_name> The configured name of the disk.

<subpath> The path of the file relative to the disk´s root (escaped).

<size> The size of the file in bytes (uint).

<mtime_sec> The file´s modification time in seconds since the Epoch (int).

<mtime_nsec> The file´s modification time nanosecond component (uint).

<inode> The file´s inode number (uint).

Logs details for a link found on a disk. The `<type>` component varies based on the kind of link.

<type> The type of link, one of: `hardlink`, `symlink`, `symdir` (symlink to a directory), `junction` (Windows-specific reparse point).

<disk_name> The configured name of the disk (string).

<subpath> The path of the link relative to the disk´s root (escaped).

<linkto> The target path of the link (escaped).

Summary Tags

These tags log final statistics about the entire listing operation.

Logs the total number of regular files processed.

<count> The total number of files (uint).

Logs the total size of all regular files processed.

<size> The cumulative size of all files (uint, bytes).

Logs the total number of links processed (hardlinks, symlinks, symdirs, junctions).

<count> The total number of links (uint).

Indicates a successful completion of the listing operation. Note that if a fatal error happens, the program will abort, and you won´t get this tag.

COMMAND DUP TAGS

This section describes the tags output with the `dup` command.

Duplicate Tags

These tags log information about detected duplicate files and provide a summary of the duplicate finding process. The content hash of the whole file is used to determine duplicates.

Logs the information about a pair of duplicate files found. The first file listed is the one just processed, and the second file is the previously processed file that has the same content hash.

<diskname1> The configured name of the disk containing the newly processed duplicate file.

<file_path1> The path of the newly processed duplicate file relative to its disk´s mount point (escaped).

<diskname2> The configured name of the disk containing the previously processed file that is the duplicate of `<file_path1>`.

<file_path2> The path of the previously processed duplicate file relative to its disk´s mount point (escaped).

<size> The size of the duplicate file in bytes (uint). This size corresponds to the file `<file_path2>`.

Summary Tags

These tags provide a final summary of the duplicate finding process.

Logs the total number of duplicate files found. A file is counted as a duplicate if its hash matches a hash already seen.

<count> The total count of duplicate files (uint).

Logs the total size of all duplicate files found. This size is the sum of the sizes of all files considered duplicates.

<size> The total size of duplicate files in gigabytes (uint).

Logs the overall exit status of the command. The `status` is one of the following:

unique Indicates that no duplicate files were found.

dup Indicates that at least one duplicate file was found.

COMMAND POOL TAGS

This section describes the tags output with the `pool` command.

Logs the total number of links created (symlinks, junctions).

<count> The total number of links (uint).

Indicates a successful completion of the pool operation. Note that if a fatal error happens, the program will abort, and you won´t get this tag.

COMMAND REHASH TAGS

This section describes the tags output with the `rehash` command.

Summary Tags

These tags provide a final summary of the rehash scheduling process.

Logs the overall exit status of the command. The `status` is one of the following:

scheduled Indicates that a rehash operation has been successfully scheduled. The rehash will be performed incrementally in future `sync` or `scrub` commands.

already_in_progress Indicates that that a rehash is already in progress and cannot be scheduled again. This causes the program to exit with a fatal error.

not_required Indicates that the current hash algorithm is already the `best hash` for the platform, and thus a rehash is not required. This causes the program to exit with a fatal error.

COMMAND SMART AND PROBE TAGS

This section describes the tags output by the `smart` and `probe` commands. The main difference between the two is that `probe` doesn´t spin up the disk, so it won´t be able to get all attributes if the disk is spun down. The `smart` command, instead, will always get all attributes, but with the risk of spinning up all disks.

Note that a `<disk_name>` may be associated with more `<device_file>`, in case the logical disk uses more physical disks. In such a case, you´ll see multiple `<attr>` and `<smart>` tags for the same `<disk_name>` but with different `<device_file>`. The exception is the `stat` attrbute that is cumulative for all the devices part of the disk.

In case of split parity, the parity name is followed by `/N` to indicate the split index, where N starts from 0. The `/0` is always omitted.

Attributes

Tags logging specific disk identification and attribute values.

Logs the start of the SMART report for a device.

<device_file> The file path of the device (e.g., /dev/sdb).

<disk_name>[/<split_index>] The configured name of the disk. In case of split parity, the parity name is followed by `/N` to indicate the split index, where N starts from 0. The `/0` is always omitted.

Logs the disk´s serial number.

<serial_number> The disk´s serial number (escaped).

Logs the disk´s model family string.

<family> The disk´s model family identifier (escaped).

Logs the disk´s model string.

<model> The disk´s model identifier (escaped).

Logs the disk´s interface. Something like `USB`, `SATA`, `NVMe`.

<interface> The disk´s interface (escaped).

Logs the estimated Annual Failure Rate (AFR) and the probability of at least one failure in the next year based on SMART attributes. The AFR is calculated using the SMART attributes (5, 187, 188, 197, 198).

<afr> The computed Annual Failure Rate (the average number of failures you expect in a year) (float).

<prob> The probability of at least one failure in the next year (float).

Logs the size of the disk.

<size_bytes> The disk size in bytes (uint).

Counts command, transport, or controller-level errors reported by the device. These reflect failed I/O operations not directly caused by media defects (for example interface, firmware, or power-related errors). This counter is cumulative and never resets to zero, even if the underlying error condition is resolved.

<error_count> The total error count (uint).

Counts media-level errors where data could not be reliably read or written. These indicate actual storage surface or flash failures and may imply data loss. This counter is cumulative and never resets to zero, even if the underlying error condition is resolved.

<error_count> The total error count (uint).

The wear level of the SSD/NVME expressed as a percentage, where a value of 0 represents a brand new drive with zero wear and a value of 100 indicates the drive has reached or exceeded its manufacturer-rated design life. This metric is provided as a normalized unsigned integer, offering a consistent health indicator across various SSD/NVME vendors and interface types by mapping diverse hardware counters into a single standardized scale.

<percentage> Wear level percentage (uint).

Logs the disk´s rotation rate.

<rate> The rotation rate. A value of 0 indicates a solid-state drive (SSD) or other non-rotating medium. A value of 1 indicates a rotational disk of unknown precise speed. Values greater than 1 indicate the rotational speed in RPM.

Logs the SMART status flags from the `smartctl` utility. Per the smartctl manpage, these flags are bit-mapped to indicate specific issues like `Command line did not parse`, `Device could not be opened`, or `SMART status check returned ´DISK FAILING´`.

<flags_decimal> The raw flags value (uint, decimal).

<flags_hex> The raw flags value (uint, hexadecimal).

Logs the raw value of any assigned SMART attribute.

<id> The SMART attribute ID (uint).

<raw_decimal> The raw attribute value (uint, decimal).

<raw_hex> The raw attribute value (uint, hexadecimal).

<norm> The normalized value (uint).

<worst> The worst value (uint).

<thresh> The threshold value (uint).

<name> Name of the attribute.

<type> Type of the attribute: `prefail` or `oldage`.

<updated> Update method of the attribute: `always` or `offline`.

<when_failed> If and when the attribute failed: `never` or `past` or `now`.

Logs that the device was confirmed to be in an active power state after a status probe.
Logs that the device was confirmed to be in a standby/spun-down state.
Logs a successful spin-up operation via direct O_DIRECT read.
Logs a successful spin-down operation initiated via the smartctl command.
Logs the total number of read and write accesses done on the disk. This is a cumulative value that include all the devices and split of the disk. Comparing this number at different times, you can detect if the disk was used during that time.

<access_number> Total number of accesses (uint).

Summary

Tags logging the overall failure probabilities for the array.

Logs the total estimated failure rate for the entire array (sum of individual disk AFRs) and the probability of at least one failure in the next year.

<array_afr> The sum of AFRs of all disks in the array (the average number of failures you expect in a year) (float).

<array_prob> The probability of at least one failure in the next year (float).

DEVICE STATUS TAGS

These tags log the lifecycle of hardware interactions and external command execution with the `smartctl` command.

Logs a failure in the command shell execution environment.

<device_file> The system path to the device node.

<disk_name>[/<split_index>] The configured name of the disk. In case of split parity, the parity name is followed by `/N` to indicate the split index, where N starts from 0. The `/0` is always omitted.

Logs a low-level system error during direct file operations. This is triggered when open(), read(), or close() calls fail during a spin-up attempt.

<errno> The standard integer error number provided by the OS.

Logs that an external process (smartctl) failed to complete normally, such as being terminated by a signal rather than exiting.
Logs that the external command (smartctl) returned a non-zero exit code that was not explicitly recognized as a valid state.

<exit_code> The integer exit status returned by the process (int).

ERROR TAGS

These tags report specific errors that occur on data disks during the commands that access files and parities.

Logs file access errors (open, read, file changed) during the data disk read operation for parity calculation or verification.

_io Indicates a physical Input/Output error. The disk was unable to read or write a specific block, typically signaling a failing sector or cable issue.

_data Indicates the data was read successfully but failed the checksum/hash verification. This signals `silent` corruption or an unsuccessful parity match.

<block> The zero-based index of the block where the error occurred (uint).

<disk_name> The name of the data disk.

<file> The path (relative to the disk mount point) of the file containing the block (escaped).

<msg> A descriptive message indicating the nature of the error (e.g., `Open/Read/Write error`, `Data error at position <pos>, diff bits <diff>/<bits>`).

Logs errors during parity disk read or write operations.

_io Indicates a physical Input/Output error. The disk was unable to read or write a specific block, typically signaling a failing sector or cable issue.

_data Indicates the data was read successfully but failed the checksum/hash verification. This signals `silent` corruption or an unsuccessful parity match.

<block> The zero-based index of the block where the error occurred (uint).

<level> The configuration name of the parity level (e.g., `parity`, `2-parity`).

<msg> A descriptive message indicating the nature of the error (e.g., `Read/Write error`, `Data error, diff bits <diff>/<bits>`).

Indicates an error when attempting to access a hard link.

<disk_name> The name of the disk.

<link_path> The hard link path relative to disk root (escaped).

<target_path> The target path of the hard link (escaped).

<msg> A descriptive message indicating the nature of the error (e.g., `Hardlink stat error`, `Hardlink error for not regular file`, `Hardlink to stat error`, `Hardlink-to error for not regular file`, `Hardlink mismatch for different inode`).

Indicates an error when attempting to access a symbolic link.

<disk_name> The name of the disk.

<link_path> The symlink path relative to disk root (escaped).

<msg> A descriptive message indicating the nature of the error (e.g., `Symlink read error`, `Symlink data error ´<actual>´ instead of ´<expected>´`).

Indicates an error when attempting to access a directory.

<disk_name> The name of the disk.

<dir_path> The directory path relative to disk root (escaped).

<msg> A descriptive message indicating the nature of the error (e.g., `Dir stat error`, `Dir error for not directory`).

Logs that a file´s blocks extend beyond the available parity space, indicating that the parity files are too small to protect all data. This occurs when data requires more parity than is available on the parity disk(s) and is a critical warning.

<disk_name> The name of the disk containing the file.

<file_path> The file path relative to the disk root (escaped).