ZFS Troubleshooting Guide
Diagnosing Potential Problems
- General commands for diagnosing hardware problems are:
zpool status
zpool status -v
fmdump
fmdump -ev or fmdump -eV
format or rmformat
- Identify hardware problems with the zpool status commands. If a pool is in the DEGRADED state, use the zpool status command to identify if a disk is unavailable. For example:
# zpool status -x
pool: zeepool
state: DEGRADED
status: One or more devices could not be opened. Sufficient replicas exist for
the pool to continue functioning in a degraded state.
action: Attach the missing device and online it using 'zpool online'.
see: http://www.sun.com/msg/ZFS-8000-D3
scrub: resilver completed after 0h12m with 0 errors on Thu Aug 28 09:29:43 2008
config:
NAME STATE READ WRITE CKSUM
zeepool DEGRADED 0 0 0
mirror DEGRADED 0 0 0
c1t2d0 ONLINE 0 0 0
spare DEGRADED 0 0 0
c2t1d0 UNAVAIL 0 0 0 cannot open
c2t3d0 ONLINE 0 0 0
spares
c1t3d0 AVAIL
c2t3d0 INUSE currently in use
errors: No known data errors
- See the disk replacement example to recover from a failed disk.
- Identify potential data corruption with the zpool status -v command. If only one file is corrupted, then you might choose to deal with it directly, without needing to restore the entire pool.
# zpool status -v rpool
pool: rpool
state: DEGRADED
status: One or more devices has experienced an error resulting in data
corruption. Applications may be affected.
action: Restore the file in question if possible. Otherwise restore the
entire pool from backup.
see: http://www.sun.com/msg/ZFS-8000-8A
scrub: scrub completed after 0h2m with 1 errors on Tue Mar 11 13:12:42 2008
config:
NAME STATE READ WRITE CKSUM
rpool DEGRADED 0 0 9
c2t0d0s0 DEGRADED 0 0 9
errors: Permanent errors have been detected in the following files:
/mnt/root/lib/amd64/libc.so.1
- Display the list of suspected faulty devices using the fmdump command. It is also useful to know the diagnosis engines available on your system and how busy they have been, which is obtained via the fmstat command. Similarly, fmadm will show the status of the diagnosis engines. You can also see that there are 4 diagnosis engines which are appropriate to devices and ZFS: disk-transport, io-retire, zfs-diagnosis, and zfs-retire. Check your OS release for the available FMA diagnosis engine capability.
# fmdump
TIME UUID SUNW-MSG-ID
Aug 18 18:32:48.1940 940422d6-03fb-4ea0-b012-aec91b8dafd3 ZFS-8000-D3
Aug 21 06:46:18.5264 692476c6-a4fa-4f24-e6ba-8edf6f10702b ZFS-8000-D3
Aug 21 06:46:18.7312 45848a75-eae5-66fe-a8ba-f8b8f81deae7 ZFS-8000-D3
# fmstat
module ev_recv ev_acpt wait svc_t %w %b open solve memsz bufsz
cpumem-retire 0 0 0.0 0.0 0 0 0 0 0 0
disk-transport 0 0 0.0 55.9 0 0 0 0 32b 0
eft 0 0 0.0 0.0 0 0 0 0 1.2M 0
fabric-xlate 0 0 0.0 0.0 0 0 0 0 0 0
fmd-self-diagnosis 0 0 0.0 0.0 0 0 0 0 0 0
io-retire 0 0 0.0 0.0 0 0 0 0 0 0
snmp-trapgen 0 0 0.0 0.0 0 0 0 0 32b 0
sysevent-transport 0 0 0.0 4501.8 0 0 0 0 0 0
syslog-msgs 0 0 0.0 0.0 0 0 0 0 0 0
zfs-diagnosis 0 0 0.0 0.0 0 0 0 0 0 0
zfs-retire 0 0 0.0 0.0 0 0 0 0 0 0
# fmadm config
MODULE VERSION STATUS DESCRIPTION
cpumem-retire 1.1 active CPU/Memory Retire Agent
disk-transport 1.0 active Disk Transport Agent
eft 1.16 active eft diagnosis engine
fabric-xlate 1.0 active Fabric Ereport Translater
fmd-self-diagnosis 1.0 active Fault Manager Self-Diagnosis
io-retire 2.0 active I/O Retire Agent
snmp-trapgen 1.0 active SNMP Trap Generation Agent
sysevent-transport 1.0 active SysEvent Transport Agent
syslog-msgs 1.0 active Syslog Messaging Agent
zfs-diagnosis 1.0 active ZFS Diagnosis Engine
zfs-retire 1.0 active ZFS Retire Agent
- Display more details about potential hardware problems by examining the error reports with fmdump -ev. Display even more details with fmdump -eV.
# fmdump -eV
TIME CLASS
Aug 18 2008 18:32:35.186159293 ereport.fs.zfs.vdev.open_failed
nvlist version: 0
class = ereport.fs.zfs.vdev.open_failed
ena = 0xd3229ac5100401
detector = (embedded nvlist)
nvlist version: 0
version = 0x0
scheme = zfs
pool = 0x4540c565343f39c2
vdev = 0xcba57455fe08750b
(end detector)
pool = whoo
pool_guid = 0x4540c565343f39c2
pool_context = 1
pool_failmode = wait
vdev_guid = 0xcba57455fe08750b
vdev_type = disk
vdev_path = /dev/ramdisk/rdx
parent_guid = 0x4540c565343f39c2
parent_type = root
prev_state = 0x1
__ttl = 0x1
__tod = 0x48aa22b3 0xb1890bd
- If expected devices can't be displayed with the format or rmformat utility, then those devices won't be visible to ZFS.
[edit] Disk Replacement Example
- To be supplied.
[edit] Problems after Disk Replacement
- If the replaced disk is not visible in the zpool status output, make sure all cables are reconnected properly.
[edit] Panic/Reboot/Pool Import Problems
During the boot process, each pool must be opened, which means that pool failures might cause a system to enter into a panic-reboot loop. In order to recover from this situation, ZFS must be informed not to look for any pools on startup.
[edit] Boot From Milestone=None Recovery Method
- Boot to the none milestone by using the -m milestone=none boot option.
ok boot -m milestone=none
- Remount your root file system as writable.
- Rename or move the /etc/zfs/zpool.cache file to another location.
These actions cause ZFS to forget that any pools exist on the system, preventing it from trying to access the bad pool causing the
problem. If you have multiple pools on the system, do these additional steps:
* Determine which pool might have issues by using the fmdump -eV command to display the pools with reported fatal errors.
* Import the pools one-by-one, skipping the pools that are having issues, as described in the fmdump output.
- If the system is back up, issue the svcadm milestone all command.
[edit] Boot From OpenSolaris Live CD Recovery Method
If you are running a Solaris SXCE or Solaris 10 release, you might be able to boot from the OpenSolaris Live CD and fix whatever is causing the pool import to fail.
- Boot from the OpenSolaris Live CD
- Import the pool
- Resolve the issue that causes the pool import to fail, such as replace a failed disk
- Export the pool (?)
- Boot from the original Solaris release
- Import the pool
[edit] Capacity Problems with Storage Array LUNs
- If you resize a LUN from a storage array and the zpool status command doesn't display the LUN's expected capacity, export and import the pool to see expected capacity. This is CR xxxxxxx.
- If zpool status doesn't display the array's LUN expected capacity, confirm that the expected capacity is visible from the format utility. For example, the format output below shows that one LUN is configured as 931.01 Gbytes and one is configured as 931.01 Mbytes.
2. c6t600A0B800049F93C0000030A48B3EA2Cd0 <SUN-LCSM100_F-0670-931.01GB>
/scsi_vhci/ssd@g600a0b800049f93c0000030a48b3ea2c
3. c6t600A0B800049F93C0000030D48B3EAB6d0 <SUN-LCSM100_F-0670-931.01MB>
/scsi_vhci/ssd@g600a0b800049f93c0000030d48b3eab6
- You will need to reconfigure the array's LUN capacity with the array sizing tool to correct this sizing problem.
- When the LUN sizes are resolved, export and import the pool if the pool has already been created with these LUNs.
[edit] Resolving Software Problems
[edit] Unsupported CIFS properties in Solaris 10 xx Release
- The Solaris 10 xx release includes modifications to support the Solaris CIFS environment as described in zfs.1m. However, the CIFS features are not supported in the Solaris 10 release. Therefore, these properties are set to read-only values. If you attempt to reset the CIFS-related properties, you will see a message similar to the following:
# zfs set utf8only=on rpool
cannot set property for 'rpool': 'utf8only' is readonly
[edit] Unsupported Cache Devices in Solaris 10 xx Release
- The Solaris 10 xx release identifies cache device support is available by using the zpool upgrade -v command. For example:
# zpool upgrade -v
This system is currently running ZFS pool version 10.
The following versions are supported:
VER DESCRIPTION
--- --------------------------------------------------------
1 Initial ZFS version
2 Ditto blocks (replicated metadata)
3 Hot spares and double parity RAID-Z
4 zpool history
5 Compression using the gzip algorithm
6 bootfs pool property
7 Separate intent log devices
8 Delegated administration
9 refquota and refreservation properties
10 Cache devices
- However, cache devices are not supported in this release.
- If you attempt to add a cache device to a ZFS storage pool when the pool is created, the following message is displayed:
# zpool create pool mirror c0t1d0 c0t2d0 cache c0t3d0
cannot create 'pool': operation not supported on this type of pool
- If you attempt to add a cache device to a ZFS storage pool after the pool is created, the following message is displayed:
# zpool create pool mirror c0t1d0 c0t2d0
# zpool add pool cache c0t3d0
cannot add to 'pool': pool must be upgraded to add these vdevs
[edit] ZFS Installation Issues
[edit] Review Solaris 10 [ ] Installation Requirements
- 768 Mbytes is the minimum amount of memory required to install a ZFS root file system
- 1 Gbyte of memory is recommended for better overall ZFS performance
- At least 16 Gbytes of disk space is recommended
[edit] Before You Start
- Due to an existing boot limitation, disks intended for a bootable ZFS root pool must be created with disk slices and must be labeled with a VTOC (SMI) disk label.
- If you relabel EFI-labeled disks with VTOC labels, be sure that the desired disk space for the root pool is in the disk slice that will be used to create the bootable ZFS pool.
[edit] Solaris/ ZFS Initial Installation
- For the OpenSolaris 2008.05 release, a ZFS root file system is installed by default and there is no option to choose another type of root file system.
- For the SXCE and Solaris 10 xx releases, you can only install a ZFS root file system from the text installer.
- You cannot use a Flash install or the standard upgrade option to install or migrate to a ZFS root file system. Stay tuned, more work is in progress on improving installation.
- For the SXCE and Solaris 10 xx releases, you can use LiveUpgrade to migrate a UFS root file system to a ZFS root file system.
- Access the text installer as follows:
* On SPARC based system, use the following syntax from the Solaris installation DVD or the network:
ok boot cdrom - text
ok boot net - text
* On an x86 based system, select the text-mode install option when presented.
- If you accidentally start the GUI install method, do the following:
* Exit the GUI installer
* Expand the terminal window to 80 x 24
* Unset the DISPLAY, like this:
# DISPLAY=
# export DISPLAY
# install-solaris
[edit] ZFS Root Pool Recommendations and Requirements
- Set up a root pool of two mirrored disks. For example:
# zpool create rpool mirror c0t0d0s0 c1t0d0s0
- You can also add a mirror later. See the ZFS Administration Guide for details.
- Solaris VTOC labels are required for disks in the root pool which should be configured using a slice specification. EFI labeled disks do not work. Several factors are at work here, including BIOS support for booting from EFI labeled disks.
- Note: If you mirror the boot disk later, make sure you specify a bootable slice and not the whole disk because the latter may try to install an EFI label.
- You cannot use a RAID-Z configuration for a root pool. Only single-disk pools or pools with mirrored disks are supported. You will see the following message if you attempt to use an unsupported pool for the root pool:
ERROR: ZFS pool <pool-name> does not support boot environments
- Root pools cannot have a separate log device. For example:
# zpool add -f rpool log c0t6d0s0
cannot add to 'rpool': root pool can not have multiple vdevs or separate logs
- The lzjb compression property is supported for root pools but the other compression types are not supported.
- Keep a second ZFS BE for recovery purposes. You can boot from alternate BE if the primary BE fails. For example:
# lucreate -n ZFS2BE
- Keep root pool snapshots on a remote system. See the steps below for details.
[edit] Solaris Live Upgrade Migration Scenarios
- You can use the Solaris Live Upgrade feature to migrate a UFS root file system to a ZFS root file system.
- You can't use Solaris Live Upgrade to migrate a ZFS boot environment (BE) to UFS BE.
- You can't use Solaris Live Upgrade to migrate non-root or shared UFS file systems to ZFS file systems.
[edit] Review LU Requirements
- You must be running the SXCE, build 90 release or the Solaris 10 xx release to use LU to migrate a UFS root file system to a ZFS root file system.
- You must create a ZFS storage pool that contains disk slices before the LU migration.
- The pool must exist either on a disk slice or on disk slices that are mirrored, but not on a RAID-Z configuration or on a nonredundant configuration of multiple disks. If you attempt to use an unsupported pool configuration during a Live Upgrade migration, you will see a message similar to the following:
ERROR: ZFS <pool-name> does not support boot environments
- If you see this message, then either the pool doesn't exist or its an unsupported configuration.
[edit] Live Upgrade Issues
- The Solaris installation GUI's standard-upgrade option is not available for migrating from a UFS to a ZFS root file system. To migrate from a UFS file system, you must use Solaris Live Upgrade.
- You cannot use Solaris Live Upgrade to create a UFS BE from a ZFS BE.
- Do not rename your ZFS BEs with the zfs rename command because the Solaris Live Upgrade feature is unaware of the name change. Subsequent commands, such as ludelete, will fail. In fact, do not rename your ZFS pools or file systems if you have existing BEs that you want to continue to use.
- Solaris Live Upgrade creates the datasets for the BE and ZFS volumes for the swap area and dump device but does not account for any existing dataset property modifications. Thus, if you want a dataset property enabled in the new BE, you must set the property before the lucreate operation. For example:
zfs set compression=on rpool/ROOT
- When creating an alternative BE that is a clone of the primary BE, you cannot use the -f, -x, -y, -Y, and -z options to include or exclude files from the primary BE. You can still use the inclusion and exclusion option set in the following cases:
UFS -> UFS UFS -> ZFS ZFS -> ZFS (different pool)
- Although you can use Solaris Live Upgrade to upgrade your UFS root file system to a ZFS root file system, you cannot use Solaris Live Upgrade to upgrade non-root or shared file systems.
[edit] Live Upgrade with Zones
[edit] ZFS Boot Issues
- Sometimes the boot process is slow. Be patient.
- CR 6704717 – Do not place offline the primary disk in a mirrored ZFS root configuration. If you do need to offline or detach a mirrored root disk for replacement, then boot from another mirrored disk in the pool.
- CR 6668666 - If you attach a disk to create a mirrored root pool after an initial installation, you will need to apply the boot blocks to the secondary disks. For example:
sparc# installboot -F zfs /usr/platform/`uname -i`/lib/fs/zfs/bootblk /dev/rdsk/c0t1d0s0
x86# installgrub /boot/grub/stage1 /boot/grub/stage2 /dev/rdsk/c0t1d0s0
- CR 6741743 - The boot -L command doesn't work if you migrated from a UFS root file system. Copy the bootlst command to the correct location. For example:
# cp -p /platform/`uname -m`/bootlst /rpool/platform/`uname -m`/bootlst
[edit] ZFS Boot Error Messages
- CR 2164779 - Ignore the following krtld messages from the boot -Z command. They are harmless:
krtld: Ignoring invalid kernel option -Z.
krtld: Unused kernel arguments: `rpool/ROOT/zfs1008BE'.
[edit] Boot From a Alternate Disk in a Mirrored ZFS Root Pool
- You can boot from different devices in a mirrored ZFS root pool. Depending on the hardware configuration, you might need to update the OpenBoot PROM configuration or the BIOS to specify a different boot device.
- You will have to identify the device pathnames for the alternate disks in the mirrored root pool. For example, identify the disks in the mirrored root pool with the zpool status command:
# zpool status
pool: rpool
state: ONLINE
scrub: resilver completed after 0h6m with 0 errors on Thu Sep 11 10:55:28 2008
config:
NAME STATE READ WRITE CKSUM
rpool ONLINE 0 0 0
mirror ONLINE 0 0 0
c0t0d0s0 ONLINE 0 0 0
c0t1d0s0 ONLINE 0 0 0
errors: No known data errors
- If you attached the second disk in the mirror configuration after an initial installation, you will need to apply the bootblocks. For example, on a SPARC system:
# installboot -F zfs /usr/platform/`uname -i`/lib/fs/zfs/bootblk /dev/rdsk/c0t1d0s0
[edit] ZFS Root Pool Recovery
[edit] Complete Solaris 10 xx Root Pool Recovery
The section describes how to create and restore root pool snapshots.
[edit] Create Root Pool Snapshots
Create root pool snapshots for recovery purposes. For example:
1. Create space on a remote system to store the snapshots.
remote# zfs create rpool/snaps
remote# zfs list
NAME USED AVAIL REFER MOUNTPOINT
rpool 108K 8.24G 19K /rpool
rpool/snaps 18K 8.24G 18K /rpool/snaps
2. Share the space to the local system.
remote# zfs set sharenfs='rw=local-system,root=local-system' rpool/snaps
# share
-@rpool/snaps /rpool/snaps sec=sys,rw=local-system,root=local-system ""
3. Create the snapshots.
local# zfs snapshot -r rpool@1016
# zfs list
NAME USED AVAIL REFER MOUNTPOINT
rpool 6.15G 27.1G 94K /rpool
rpool@1016 0 - 94K -
rpool/ROOT 4.64G 27.1G 18K legacy
rpool/ROOT@1016 0 - 18K -
rpool/ROOT/s10s_u6wos_07a 4.64G 27.1G 4.64G /
rpool/ROOT/s10s_u6wos_07a@1016 0 - 4.64G -
rpool/dump 1.00G 27.1G 1.00G -
rpool/dump@1016 0 - 1.00G -
rpool/export 38K 27.1G 20K /export
rpool/export@1016 0 - 20K -
rpool/export/home 18K 27.1G 18K /export/home
rpool/export/home@1016 0 - 18K -
rpool/swap 524M 27.6G 11.6M -
rpool/swap@1016 0 - 11.6M -
[edit] Recreate Pool and Restore Root Pool Snapshots
In this scenario, assume the following conditions:
- ZFS root pool cannot be recovered
- ZFS root pool snapshots are stored on a remote system and shared over NFS
All the steps below are performed on the local system.
1. Boot from CD/DVD or the network.
ok boot net
or
ok boot cdrom
Then, exit out of the installation program.
2. Mount the remote snapshot dataset.
# mount -F nfs remote:/rpool/snaps /mnt
3. Recreate the root pool. For example:
# zpool create -f -o failmode=continue -R /a -m legacy -o cachefile=/etc/zfs/zpool.cache rpool c1t1d0s0
4. Restore the root pool snapshots. This step might take some time. For example:
# cat /mnt/rpool1016 | zfs receive -Fd rpool
5. Verify that the root pool datasets are restored:
# zfs list
NAME USED AVAIL REFER MOUNTPOINT
rpool 5.65G 27.6G 94K /rpool
rpool@1016 0 - 94K -
rpool/ROOT 4.64G 27.6G 18K legacy
rpool/ROOT@1016 0 - 18K -
rpool/ROOT/s10s_u6wos_07a 4.64G 27.6G 4.64G /
rpool/ROOT/s10s_u6wos_07a@1016 4.53M - 4.63G -
rpool/dump 1.00G 27.6G 1.00G -
rpool/dump@1016 16K - 1.00G -
rpool/export 54K 27.6G 20K /export
rpool/export@1016 16K - 20K -
rpool/export/home 18K 27.6G 18K /export/home
rpool/export/home@1016 0 - 18K -
rpool/swap 11.6M 27.6G 11.6M -
rpool/swap@1016 0 - 11.6M -
6. Set the bootfs property.
# zpool set bootfs=rpool/ROOT/s10s_u6wos_07 rpool
7. Reboot the system.
# init 6
[edit] Rolling Back a Root Pool Snapshot From a Failsafe Boot
This procedure assumes that existing root pool snapshots are available. In this example, the root pool snapshots are available on the local system.
# zfs snapshot -r rpool/ROOT@1013
# zfs list
NAME USED AVAIL REFER MOUNTPOINT
rpool 5.67G 1.04G 21.5K /rpool
rpool/ROOT 4.66G 1.04G 18K /rpool/ROOT
rpool/ROOT@1013 0 - 18K -
rpool/ROOT/zfs1008 4.66G 1.04G 4.66G /
rpool/ROOT/zfs1008@1013 0 - 4.66G -
rpool/dump 515M 1.04G 515M -
rpool/swap 513M 1.54G 16K -
1. Shutdown the system and boot failsafe mode.
ok boot -F failsafe
Multiple OS instances were found. To check and mount one of them
read-write under /a, select it from the following list. To not mount
any, select 'q'.
1 /dev/dsk/c0t1d0s0 Solaris 10 xx SPARC
2 rpool:5907401335443048350 ROOT/zfs1008
Please select a device to be mounted (q for none) [?,??,q]: 2
mounting rpool on /a
2. Rollback the root pool snapshots.
# zfs rollback -rf rpool/ROOT@1013
3. Reboot back to multiuser mode.
# init 6
[edit] Primary Mirror Disk in a ZFS Root Pool is Unavailable or Fails
- If the primary disk in the pool fails, you will need to boot from the secondary disk by specifying the boot path. For example, on a SPARC system, a devalias is available to boot from the second disk as disk1.
ok boot disk1
- While booted from a secondary disk, physically replace the primary disk. For example, c0t0d0s0.
- Put a VTOC label on the new disk with format -e.
- Let ZFS know the primary disk was physically replaced at the same location.
# zpool replace rpool c0t0d0s0
- If the zpool replace step fails, detach and attach the primary mirror disk:
# zpool detach rpool c0t0d0s0
# zpool attach rpool c0t1d0s0 c0t0d0s0
- Confirm that the disk is available and the pool is resilvered.
# zpool status rpool
- Replace the bootblocks on the primary disk.
# installboot -F zfs /usr/platform/`uname -i`/lib/fs/zfs/bootblk /dev/rdsk/c0t0d0s0
- Confirm that you can boot from the primary disk.
[edit] ZFS Swap and Dump Devices
During an initial installation or a Solaris Live Upgrade from a UFS file system, a swap area is created on a ZFS volume in the ZFS root pool. The swap area size is based on half the size of physical memory, but no more than 2 Gbytes and no less than 512 Mbytes. During an initial installation or a Solaris Live Upgrade from a UFS file system, a dump device is created on a ZFS volume in the ZFS root pool. The dump device size is based on half the size of physical memory, but no more than 2 Gbytes and no less than 512 Mbytes.
# zfs list
NAME USED AVAIL REFER MOUNTPOINT
rpool 5.66G 27.6G 21.5K /rpool
rpool/ROOT 4.65G 27.6G 18K /rpool/ROOT
rpool/ROOT/zfs1008BE 4.65G 27.6G 4.65G /
rpool/dump 515M 27.6G 515M -
rpool/swap 513M 28.1G 16K -
[edit] Resizing ZFS Swap and Dump Devices
- You can adjust the size of your swap and dump volumes during an initial installation.
- You can create and size your swap and dump volumes before you do a Solaris Live Upgrade operation. For example:
# zpool create rpool mirror c0t0d0s0 c0t1d0s0
# zfs create -V 2G -b 128k rpool/dump
SPARC# zfs create -V 2G -b 8k rpool/swap
x86# zfs create -V 2G -b 4k rpool/swap
- Solaris Live Upgrade does not resize existing swap and dump volumes. You can reset the volsize property of the swap and dump devices after a system is installed. For example:
# zfs set volsize=2G rpool/dump
# zfs get volsize rpool/dump
NAME PROPERTY VALUE SOURCE
rpool/dump volsize 2G -
- You can adjust the size of the swap and dump volumes in a JumpStart profile by using profile syntax similar to the following:
install_type initial_install
cluster SUNWCXall
pool rpool 16g 2g 2g c0t0d0s0
- In this profile, the 2g and 2g entries set the size of the swap area and dump device as 2 Gbytes and 2 Gbytes, respectively.
[edit] Destroying a Pool With an Active Dump/Swap Device
If you want to destroy a ZFS root pool that is no longer needed, but it still has an active dump device and swap area, you'll need to use the dumpadm and swap commands to remove the dump device and swap area. Then, use these commands to establish a new dump device and swap area.
# dumpadm -d swap
# dumpadm -d none
< destroy the root pool >
# swap -a <device-name>
# dumpadm -d swap