zfs-events.5

ZFS-EVENTS(5) File Formats Manual ZFS-EVENTS(5)

zfs-events - Events created by the ZFS filesystem.

Description of the different events generated by the ZFS stack.

Most of these don't have any description. The events generated by ZFS have never been publicly documented. What is here is intended as a starting point to provide documentation for all possible events.

To view all events created since the loading of the ZFS infrastructure (i.e, "the module"), run

zpool events

to get a short list, and

zpool events -v

to get a full detail of the events and what information is available about it.

This man page lists the different subclasses that are issued in the case of an event. The full event name would be ereport.fs.zfs.SUBCLASS, but we only list the last part here.

checksum

Issued when a checksum error have been detected.

io

Issued when there is an I/O error in a vdev in the pool.

data

Issued when there have been data errors in the pool.

delay

Issued when an I/O was slow to complete as defined by the zio_delay_max module option.

config.sync

Issued every time a vdev change have been done to the pool.

zpool

Issued when a pool cannot be imported.

zpool.destroy

Issued when a pool is destroyed.

zpool.export

Issued when a pool is exported.

zpool.import

Issued when a pool is imported.

zpool.reguid

Issued when a REGUID (new unique identifier for the pool have been regenerated) have been detected.

vdev.unknown

Issued when the vdev is unknown. Such as trying to clear device errors on a vdev that have failed/been kicked from the system/pool and is no longer available.

vdev.open_failed

Issued when a vdev could not be opened (because it didn't exist for example).

vdev.corrupt_data

Issued when corrupt data have been detected on a vdev.

vdev.no_replicas

Issued when there are no more replicas to sustain the pool. This would lead to the pool being DEGRADED.

vdev.bad_guid_sum

Issued when a missing device in the pool have been detected.

vdev.too_small

Issued when the system (kernel) have removed a device, and ZFS notices that the device isn't there any more. This is usually followed by a probe_failure event.

vdev.bad_label

Issued when the label is OK but invalid.

vdev.bad_ashift

Issued when the ashift alignment requirement has increased.

vdev.remove

Issued when a vdev is detached from a mirror (or a spare detached from a vdev where it have been used to replace a failed drive - only works if the original drive have been readded).

vdev.clear

Issued when clearing device errors in a pool. Such as running zpool clear on a device in the pool.

vdev.check

Issued when a check to see if a given vdev could be opened is started.

vdev.spare

Issued when a spare have kicked in to replace a failed device.

vdev.autoexpand

Issued when a vdev can be automatically expanded.

io_failure

Issued when there is an I/O failure in a vdev in the pool.

probe_failure

Issued when a probe fails on a vdev. This would occur if a vdev have been kicked from the system outside of ZFS (such as the kernel have removed the device).

log_replay

Issued when the intent log cannot be replayed. The can occur in the case of a missing or damaged log device.

resilver.start

Issued when a resilver is started.

resilver.finish

Issued when the running resilver have finished.

scrub.start

Issued when a scrub is started on a pool.

scrub.finish

Issued when a pool have finished scrubbing.

bootfs.vdev.attach

This is the payload (data, information) that accompanies an event.

For zed(8), these are set to uppercase and prefixed with ZEVENT_.

pool

Pool name.

pool_failmode

Failmode - wait, continue or panic. See pool(8) (failmode property) for more information.

pool_guid

The GUID of the pool.

pool_context

The load state for the pool (0=none, 1=open, 2=import, 3=tryimport, 4=recover 5=error).

vdev_guid

The GUID of the vdev in question (the vdev failing or operated upon with zpool clear etc).

vdev_type

Type of vdev - disk, file, mirror etc. See zpool(8) under Virtual Devices for more information on possible values.

vdev_path

Full path of the vdev, including any -partX.

vdev_devid

ID of vdev (if any).

vdev_fru

Physical FRU location.

vdev_state

State of vdev (0=uninitialized, 1=closed, 2=offline, 3=removed, 4=failed to open, 5=faulted, 6=degraded, 7=healthy).

vdev_ashift

The ashift value of the vdev.

vdev_complete_ts

The time the last I/O completed for the specified vdev.

vdev_delta_ts

The time since the last I/O completed for the specified vdev.

vdev_spare_paths

List of spares, including full path and any -partX.

vdev_spare_guids

GUID(s) of spares.

vdev_read_errors

How many read errors that have been detected on the vdev.

vdev_write_errors

How many write errors that have been detected on the vdev.

vdev_cksum_errors

How many checkum errors that have been detected on the vdev.

parent_guid

GUID of the vdev parent.

parent_type

Type of parent. See vdev_type.

parent_path

Path of the vdev parent (if any).

parent_devid

ID of the vdev parent (if any).

zio_objset

The object set number for a given I/O.

zio_object

The object number for a given I/O.

zio_level

The block level for a given I/O.

zio_blkid

The block ID for a given I/O.

zio_err

The errno for a failure when handling a given I/O.

zio_offset

The offset in bytes of where to write the I/O for the specified vdev.

zio_size

The size in bytes of the I/O.

zio_flags

The current flags describing how the I/O should be handled. See the I/O FLAGS section for the full list of I/O flags.

zio_stage

The current stage of the I/O in the pipeline. See the I/O STAGES section for a full list of all the I/O stages.

zio_pipeline

The valid pipeline stages for the I/O. See the I/O STAGES section for a full list of all the I/O stages.

zio_delay

The time in ticks (HZ) required for the block layer to service the I/O. Unlike zio_delta this does not include any vdev queuing time and is therefore solely a measure of the block layer performance. On most modern Linux systems HZ is defined as 1000 making a tick equivalent to 1 millisecond.

zio_timestamp

The time when a given I/O was submitted.

zio_delta

The time required to service a given I/O.

prev_state

The previous state of the vdev.

cksum_expected

The expected checksum value.

cksum_actual

The actual/current checksum value.

cksum_algorithm

Checksum algorithm used. See zfs(8) for more information on checksum algorithms available.

cksum_byteswap

Checksum value is byte swapped.

bad_ranges

Checksum bad offset ranges.

bad_ranges_min_gap

Checksum allowed minimum gap.

bad_range_sets

Checksum for each range the number of bits set.

bad_range_clears

Checksum for each range the number of bits cleared.

bad_set_bits

Checksum array of bits set.

bad_cleared_bits

Checksum array of bits cleared.

bad_set_histogram

Checksum histogram of set bits by bit number in a 64-bit word.

bad_cleared_histogram

Checksum histogram of cleared bits by bit number in a 64-bit word.

The ZFS I/O pipeline is comprised of various stages which are defined below. The individual stages are used to construct these basic I/O operations: Read, Write, Free, Claim, and Ioctl. These stages may be set on an event to describe the life cycle of a given I/O.

Stage Bit Mask Operations
ZIO_STAGE_OPEN 0x00000001 RWFCI
ZIO_STAGE_READ_BP_INIT 0x00000002 R----
ZIO_STAGE_FREE_BP_INIT 0x00000004 --F--
ZIO_STAGE_ISSUE_ASYNC 0x00000008 RWF--
ZIO_STAGE_WRITE_BP_INIT 0x00000010 -W---
ZIO_STAGE_CHECKSUM_GENERATE 0x00000020 -W---
ZIO_STAGE_NOP_WRITE 0x00000040 -W---
ZIO_STAGE_DDT_READ_START 0x00000080 R----
ZIO_STAGE_DDT_READ_DONE 0x00000100 R----
ZIO_STAGE_DDT_WRITE 0x00000200 -W---
ZIO_STAGE_DDT_FREE 0x00000400 --F--
ZIO_STAGE_GANG_ASSEMBLE 0x00000800 RWFC-
ZIO_STAGE_GANG_ISSUE 0x00001000 RWFC-
ZIO_STAGE_DVA_ALLOCATE 0x00002000 -W---
ZIO_STAGE_DVA_FREE 0x00004000 --F--
ZIO_STAGE_DVA_CLAIM 0x00008000 ---C-
ZIO_STAGE_READY 0x00010000 RWFCI
ZIO_STAGE_VDEV_IO_START 0x00020000 RW--I
ZIO_STAGE_VDEV_IO_DONE 0x00040000 RW--I
ZIO_STAGE_VDEV_IO_ASSESS 0x00080000 RW--I
ZIO_STAGE_CHECKSUM_VERIFY0 0x00100000 R----
ZIO_STAGE_DONE 0x00200000 RWFCI

Every I/O in the pipeline contains a set of flags which describe its function and are used to govern its behavior. These flags will be set in an event as an zio_flags payload entry.

Flag Bit Mask
ZIO_FLAG_DONT_AGGREGATE 0x00000001
ZIO_FLAG_IO_REPAIR 0x00000002
ZIO_FLAG_SELF_HEAL 0x00000004
ZIO_FLAG_RESILVER 0x00000008
ZIO_FLAG_SCRUB 0x00000010
ZIO_FLAG_SCAN_THREAD 0x00000020
ZIO_FLAG_PHYSICAL 0x00000040
ZIO_FLAG_CANFAIL 0x00000080
ZIO_FLAG_SPECULATIVE 0x00000100
ZIO_FLAG_CONFIG_WRITER 0x00000200
ZIO_FLAG_DONT_RETRY 0x00000400
ZIO_FLAG_DONT_CACHE 0x00000800
ZIO_FLAG_NODATA 0x00001000
ZIO_FLAG_INDUCE_DAMAGE 0x00002000
ZIO_FLAG_IO_RETRY 0x00004000
ZIO_FLAG_PROBE 0x00008000
ZIO_FLAG_TRYHARD 0x00010000
ZIO_FLAG_OPTIONAL 0x00020000
ZIO_FLAG_DONT_QUEUE 0x00040000
ZIO_FLAG_DONT_PROPAGATE 0x00080000
ZIO_FLAG_IO_BYPASS 0x00100000
ZIO_FLAG_IO_REWRITE 0x00200000
ZIO_FLAG_RAW 0x00400000
ZIO_FLAG_GANG_CHILD 0x00800000
ZIO_FLAG_DDT_CHILD 0x01000000
ZIO_FLAG_GODFATHER 0x02000000
ZIO_FLAG_NOPWRITE 0x04000000
ZIO_FLAG_REEXECUTED 0x08000000
ZIO_FLAG_DELEGATED 0x10000000
ZIO_FLAG_FASTWRITE 0x20000000
June 6, 2015