zpool detachしようとしたらno valid replicasと言われたでござる

ZFSプールが手狭になったため、HDDを順繰り大容量のものにzpool replaceしてた。

$ zpool status zdata
  pool: zdata
 state: ONLINE
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://illumos.org/msg/ZFS-8000-8A
  scan: resilvered 8.82T in 25h57m with 2 errors on Tue Jan 23 22:47:38 2018
config:

	NAME             STATE     READ WRITE CKSUM
	zdata            ONLINE       0     0     2
	  raidz1-0       ONLINE       0     0     4
	    ada3p1       ONLINE       0     0     0
	    ada2p1       ONLINE       0     0     0
	    replacing-2  ONLINE       0     0     0
	      ada1p1     ONLINE       0     0     0
	      da0p1      ONLINE       0     0     0
	    ada5p1       ONLINE       0     0     0
	logs
	  mirror-1       ONLINE       0     0     0
	    ada6p5       ONLINE       0     0     0
	    ada7p5       ONLINE       0     0     0

errors: 2 data errors, use '-v' for a list

replace-2でada1p1をda0p1にreplaceしてた感じ。置き換え中のデバイスには(resilvering)表記が付くのだが、ご覧の通り上記のda0p1には付いてない。てなもんで、処理が終わったと判断し、ada1p1を切り離そうとしたら…

# zpool detach zdata ada1p1
cannot detach ada1p1: no valid replicas

と、言われてしまった所で日記タイトルなのである。

「有効なレプリカがない」とな…。ZFS暦7年目にして初めて目にするエラーでござる。errors: 2 data errors, use '-v' for a listで報告された壊れているファイルを消してもダメぽ。それどころか、、、

# zpool status -v zdata
  pool: zdata
 state: ONLINE
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://illumos.org/msg/ZFS-8000-8A
  scan: resilvered 8.82T in 25h57m with 2 errors on Tue Jan 23 22:47:38 2018
config:

	NAME             STATE     READ WRITE CKSUM
	zdata            ONLINE       0     0     0
	  raidz1-0       ONLINE       0     0     0
	    ada3p1       ONLINE       0     0     0
	    ada2p1       ONLINE       0     0     0
	    replacing-2  ONLINE       0     0     0
	      ada1p1     ONLINE       0     0     0
	      da0p1      ONLINE       0     0     0
	    ada5p1       ONLINE       0     0     0
	logs
	  mirror-1       ONLINE       0     0     0
	    ada6p5       ONLINE       0     0     0
	    ada7p5       ONLINE       0     0     0

errors: Permanent errors have been detected in the following files:

        zdata/NFC/data/Decomo:<0x196090>

なんやねん、zdata/NFC/data/Decomo:<0x196090>って。こうなったら神頼みのzpool scrubするしかない。

# zpool scrub zdata
$ zpool status zdata
  pool: zdata
 state: ONLINE
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://illumos.org/msg/ZFS-8000-8A
  scan: scrub in progress since Tue Jan 23 23:39:17 2018
        100G scanned out of 18.1T at 427M/s, 12h15m to go
        25.0G repaired, 0.54% done
config:

	NAME             STATE     READ WRITE CKSUM
	zdata            ONLINE       0     0     0
	  raidz1-0       ONLINE       0     0     0
	    ada3p1       ONLINE       0     0     0
	    ada2p1       ONLINE       0     0     0
	    replacing-2  ONLINE       0     0     0
	      ada1p1     ONLINE       0     0     0
	      da0p1      ONLINE       0     0     0  (repairing)
	    ada5p1       ONLINE       0     0     0
	logs
	  mirror-1       ONLINE       0     0     0
	    ada6p5       ONLINE       0     0     0
	    ada7p5       ONLINE       0     0     0

修復が始まった。replaceでのresilveringは一体なんだったのか…。しばらく放置してからプールの状態を見てみると、、、

$ zpool status zdata
  pool: zdata
 state: ONLINE
status: Some supported features are not enabled on the pool. The pool can
	still be used, but some features are unavailable.
action: Enable all features using 'zpool upgrade'. Once this is done,
	the pool may no longer be accessible by software that does not support
	the features. See zpool-features(7) for details.
  scan: scrub repaired 4.51T in 15h42m with 0 errors on Wed Jan 24 15:21:24 2018
config:

	NAME        STATE     READ WRITE CKSUM
	zdata       ONLINE       0     0     0
	  raidz1-0  ONLINE       0     0     0
	    ada3p1  ONLINE       0     0     0
	    ada2p1  ONLINE       0     0     0
	    da0p1   ONLINE       0     0     0
	    ada5p1  ONLINE       0     0     0
	logs
	  mirror-1  ONLINE       0     0     0
	    ada6p5  ONLINE       0     0     0
	    ada7p5  ONLINE       0     0     0

errors: No known data errors

修復が終わりデバイスの置き換えまで行われてる！

今回得た知見：

• zpool replaceでは、新しいデバイスの再同期が終わると旧デバイスが自動でdetachされる
• 可能ならzpool replace前にscrubでプールの状態を確認するのが吉