ZFS mirror and
Instead of hunting down add dd'ing every pending sector like was shown on the previous page you could instruct ZFS to rewrite the entire partition.
Reallocating of the sectors only happens on write so by detaching/reattaching the partition you overwrite every sector there.
# gpart show -l ada1
=> 34 72303773 ada1 GPT (34G)
34 128 1 (null) (64k)
162 4194304 2 swap0 (2.0G)
4194466 68109341 3 system0 (32G)
# zpool status system
pool: system
state: ONLINE
scan: scrub repaired 0 in 0h35m with 0 errors on Thu Dec 1 18:05:34 2011
config:
NAME STATE READ WRITE CKSUM
system ONLINE 0 0 0
mirror-0 ONLINE 0 0 0
gpt/system0 ONLINE 0 0 0
gpt/system1 ONLINE 0 0 0
errors: No known data errors
# zpool detach system gpt/system0
# zpool attach system gpt/system1 gpt/system0
The order of devices in the command above is important. The first device (gpt/system1 here) is the one that is online, the second one (gpt/system0) is the new one.
# zpool status system
pool: system
state: ONLINE
status: One or more devices is currently being resilvered. The pool will
continue to function, possibly in a degraded state.
action: Wait for the resilver to complete.
scan: resilver in progress since Fri Dec 2 15:50:43 2011
1023M scanned out of 22.1G at 6.69M/s, 0h53m to go
1023M resilvered, 4.51% done
config:
NAME STATE READ WRITE CKSUM
system ONLINE 0 0 0
mirror-0 ONLINE 0 0 0
gpt/system1 ONLINE 0 0 0
gpt/system0 ONLINE 0 0 0 (resilvering)
errors: No known data errors
Some time later:
# smartctl -A /dev/ada1 smartctl 5.42 2011-10-20 r3458 [FreeBSD 9.0-RC1 amd64] (local build) Copyright (C) 2002-11 by Bruce Allen, http://smartmontools.sourceforge.net === START OF READ SMART DATA SECTION === SMART Attributes Data Structure revision number: 16 Vendor Specific SMART Attributes with Thresholds: ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE 1 Raw_Read_Error_Rate 0x000b 200 200 051 Pre-fail Always - 0 3 Spin_Up_Time 0x0007 167 166 021 Pre-fail Always - 2691 4 Start_Stop_Count 0x0032 099 099 040 Old_age Always - 1740 5 Reallocated_Sector_Ct 0x0033 200 200 140 Pre-fail Always - 0 7 Seek_Error_Rate 0x000a 200 200 051 Old_age Always - 0 9 Power_On_Hours 0x0032 067 067 000 Old_age Always - 24147 10 Spin_Retry_Count 0x0012 100 100 051 Old_age Always - 0 11 Calibration_Retry_Count 0x0012 100 100 051 Old_age Always - 0 12 Power_Cycle_Count 0x0032 099 099 000 Old_age Always - 1622 194 Temperature_Celsius 0x0022 096 094 000 Old_age Always - 47 196 Reallocated_Event_Count 0x0032 200 200 000 Old_age Always - 0 197 Current_Pending_Sector 0x0012 200 200 000 Old_age Always - 0 198 Offline_Uncorrectable 0x0012 200 200 000 Old_age Always - 0 199 UDMA_CRC_Error_Count 0x000a 200 253 000 Old_age Always - 1 200 Multi_Zone_Error_Rate 0x0008 200 200 051 Old_age Offline - 1
So the sector was overwritten and cleared during resilvering of the device. Don't reboot until resilvering is over.
I had a similar problem but was unable to force the disk to resilver except by wiping the entire drive. I was off-lining and then trying to replace however rather than using detach/attach as you have done.
Is the order special? Does attaching the first vdev (system0) after the second cause the first to be resilvered from the second?
Is the order special? Does attaching the first vdev (system0) after the second cause the first to be resilvered from the second?
Sorry, I don't get it. Order of what?
Order of the devices in this command?
# zpool attach system gpt/system1 gpt/system0
If so, then yes, order is important. The first device is currently part of the mirror and is online. The second one is the new device. ZFS resilvers it immediately. See zpool(8).
No need to take the device offline. Because while the device is offline, no attempt is made to read or write to the device. And you need the faulty sector to be rewritten, as reallocation of pending sectors only happens on write.
Order of the devices in this command?
# zpool attach system gpt/system1 gpt/system0
If so, then yes, order is important. The first device is currently part of the mirror and is online. The second one is the new device. ZFS resilvers it immediately. See zpool(8).
No need to take the device offline. Because while the device is offline, no attempt is made to read or write to the device. And you need the faulty sector to be rewritten, as reallocation of pending sectors only happens on write.
Yes, I was asking if that order was important. I thought when I had tried that before zfs just recognized that the recently reattached drive already contained a copy of the mirror and didn't force a resilver.
I'll try this again next time.
I'll try this again next time.
