Estou criando quatro volumes de quatro snapshots do EBS na AWS. Os quatro volumes formam uma unidade multi-dispositivo BTRFS. As unidades não têm tabelas de partição, ou seja, eu corri mkfs.btrfs /dev/xvdf /dev/xvdg etc.
Quando eu crio os volumes, anexei-os com a ferramenta AWS CLI e, em seguida, execute btrfs device scan /dev/xvd{f,g,h,i} . Os dispositivos têm um rótulo, então para montá-los eu corro (eu tentei algumas coisas) mount -t btrfs -o ro,nospace_cache,clear_cache -L LABEL /tmp/dir . Isso paira por um bom tempo, 15-20 minutos. Os dispositivos são cada 2TB.
Quando eu olho no dmesg eu vejo as mensagens abaixo. Enquanto o dmesg está travando, nenhuma saída adicional aparece no dmesg. Não sei o que mais devo verificar para ver o que está causando esse problema.
[ 3316.093665] blkfront: xvdf: barrier or flush: disabled; persistent grants: enabled; indirect descriptors: enabled;
[ 3316.124269] xvdf: unknown partition table
[ 3316.430563] btrfs: device label BtrFcdData devid 1 transid 592370 /dev/xvdf
[ 3316.432660] btrfs: device label BtrFcdData devid 1 transid 592370 /dev/xvdf
[ 3317.067647] blkfront: xvdg: barrier or flush: disabled; persistent grants: enabled; indirect descriptors: enabled;
[ 3317.111985] xvdg: unknown partition table
[ 3317.450861] btrfs: device label BtrFcdData devid 2 transid 592370 /dev/xvdg
[ 3317.453036] btrfs: device label BtrFcdData devid 2 transid 592370 /dev/xvdg
[ 3318.186270] blkfront: xvdh: barrier or flush: disabled; persistent grants: enabled; indirect descriptors: enabled;
[ 3318.232822] xvdh: unknown partition table
[ 3319.025208] btrfs: device label BtrFcdData devid 3 transid 592370 /dev/xvdh
[ 3319.027380] btrfs: device label BtrFcdData devid 3 transid 592370 /dev/xvdh
[ 3320.067903] blkfront: xvdi: barrier or flush: disabled; persistent grants: enabled; indirect descriptors: enabled;
[ 3320.123265] xvdi: unknown partition table
[ 3320.495547] btrfs: device label BtrFcdData devid 4 transid 592370 /dev/xvdi
[ 3320.497922] btrfs: device label BtrFcdData devid 4 transid 592370 /dev/xvdi
[ 3321.436803] btrfs: device label BtrFcdData devid 1 transid 592370 /dev/xvdf
[ 3321.437252] btrfs: device label BtrFcdData devid 2 transid 592370 /dev/xvdg
[ 3321.437641] btrfs: device label BtrFcdData devid 3 transid 592370 /dev/xvdh
[ 3321.438040] btrfs: device label BtrFcdData devid 4 transid 592370 /dev/xvdi
[ 3457.266257] blkfront: xvdf: barrier or flush: disabled; persistent grants: enabled; indirect descriptors: enabled;
[ 3457.315871] xvdf: unknown partition table
[ 3457.862287] btrfs: device label BtrFcdData devid 1 transid 592370 /dev/xvdf
[ 3457.864513] btrfs: device label BtrFcdData devid 1 transid 592370 /dev/xvdf
[ 3458.413241] blkfront: xvdg: barrier or flush: disabled; persistent grants: enabled; indirect descriptors: enabled;
[ 3458.519586] xvdg: unknown partition table
[ 3458.941200] btrfs: device label BtrFcdData devid 2 transid 592370 /dev/xvdg
[ 3458.943531] btrfs: device label BtrFcdData devid 2 transid 592370 /dev/xvdg
[ 3460.121281] blkfront: xvdh: barrier or flush: disabled; persistent grants: enabled; indirect descriptors: enabled;
[ 3460.198695] xvdh: unknown partition table
[ 3460.805858] btrfs: device label BtrFcdData devid 3 transid 592370 /dev/xvdh
[ 3460.808173] btrfs: device label BtrFcdData devid 3 transid 592370 /dev/xvdh
[ 3461.146042] blkfront: xvdi: barrier or flush: disabled; persistent grants: enabled; indirect descriptors: enabled;
[ 3461.271872] xvdi: unknown partition table
[ 3462.355409] btrfs: device label BtrFcdData devid 4 transid 592370 /dev/xvdi
[ 3462.357822] btrfs: device label BtrFcdData devid 4 transid 592370 /dev/xvdi
[ 3463.185250] btrfs: device label BtrFcdData devid 1 transid 592370 /dev/xvdf
[ 3463.185669] btrfs: device label BtrFcdData devid 2 transid 592370 /dev/xvdg
[ 3463.186098] btrfs: device label BtrFcdData devid 3 transid 592370 /dev/xvdh
[ 3463.186471] btrfs: device label BtrFcdData devid 4 transid 592370 /dev/xvdi
[ 3463.217317] btrfs: device label BtrFcdData devid 4 transid 592370 /dev/xvdi
[ 3463.219230] btrfs: disabling disk space caching
[ 3463.219233] btrfs: force clearing of disk cache
[ 4930.891445] btrfs: device fsid e512929a-72e4-4bf9-bf1d-c4744bb9cb06 devid 2 transid 27031 /dev/xvdb
[ 4930.893685] btrfs: device fsid e512929a-72e4-4bf9-bf1d-c4744bb9cb06 devid 2 transid 27031 /dev/xvdb
[ 4930.949380] btrfs: device fsid e512929a-72e4-4bf9-bf1d-c4744bb9cb06 devid 1 transid 27031 /dev/xvdc
[ 4930.951209] btrfs: device fsid e512929a-72e4-4bf9-bf1d-c4744bb9cb06 devid 1 transid 27031 /dev/xvdc
[ 4937.133509] btrfs: device fsid e512929a-72e4-4bf9-bf1d-c4744bb9cb06 devid 2 transid 27031 /dev/xvdb
[ 4937.135297] btrfs: device fsid e512929a-72e4-4bf9-bf1d-c4744bb9cb06 devid 2 transid 27031 /dev/xvdb
[ 4937.135757] btrfs: device fsid e512929a-72e4-4bf9-bf1d-c4744bb9cb06 devid 1 transid 27031 /dev/xvdc
[ 4937.137575] btrfs: device fsid e512929a-72e4-4bf9-bf1d-c4744bb9cb06 devid 1 transid 27031 /dev/xvdc
Editar:
A execução de watch iostat -dk 2 -x 1 mostra alguns números diferentes. A princípio, ele mostrava uma alta utilização nos dois primeiros dispositivos e mostra isso:
Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util
xvda 0.01 1.49 0.87 2.99 22.34 274.17 153.71 1.62 419.08 5.06 540.15 3.91 1.51
xvdd 0.00 0.00 0.02 0.00 0.07 0.00 7.91 0.00 0.41 0.41 0.00 0.41 0.00
xvdb 0.00 0.10 1.53 1.59 23.88 31.80 35.69 0.16 52.79 5.00 98.68 2.80 0.87
xvdc 0.00 0.08 1.58 1.37 24.99 27.43 35.49 0.25 84.70 5.21 176.74 3.45 1.02
xvdf 0.00 2.11 0.48 13.36 7.44 1325.75 192.64 2.25 162.64 5.33 168.27 2.18 3.01
xvdt 0.00 0.00 0.01 0.00 0.08 0.00 31.25 0.00 77.77 77.77 0.00 72.35 0.04
xvdy 0.00 0.00 0.00 0.00 0.03 0.00 30.32 0.00 102.43 102.43 0.00 101.05 0.02
xvdu 0.00 0.00 0.00 0.00 0.00 0.00 20.96 0.00 75.64 75.64 0.00 75.64 0.00
xvdo 0.00 0.00 0.00 0.00 0.01 0.00 16.84 0.00 38.53 38.53 0.00 38.53 0.00
Este é um trecho do syslog:
Nov 23 17:35:01 ip-10-0-1-123 CRON[11806]: (root) CMD (command -v debian-sa1 > /dev/null && debian-sa1 1 1)
Nov 23 17:38:28 ip-10-0-1-123 kernel: [605946.625013] blkfront: xvdt: barrier or flush: disabled; persistent grants: enabled; indirect descriptors: enabled;
Nov 23 17:38:28 ip-10-0-1-123 kernel: [605946.732903] xvdt: unknown partition table
Nov 23 17:38:28 ip-10-0-1-123 kernel: [605947.017249] btrfs: device label BtrFcdData devid 1 transid 616951 /dev/xvdt
Nov 23 17:38:29 ip-10-0-1-123 kernel: [605947.036501] btrfs: device label BtrFcdData devid 1 transid 616951 /dev/xvdt
Nov 23 17:38:30 ip-10-0-1-123 kernel: [605948.575945] blkfront: xvdy: barrier or flush: disabled; persistent grants: enabled; indirect descriptors: enabled;
Nov 23 17:38:30 ip-10-0-1-123 kernel: [605948.624099] xvdy: unknown partition table
Nov 23 17:38:30 ip-10-0-1-123 kernel: [605948.944109] btrfs: device label BtrFcdData devid 2 transid 616951 /dev/xvdy
Nov 23 17:38:30 ip-10-0-1-123 kernel: [605948.946964] btrfs: device label BtrFcdData devid 2 transid 616951 /dev/xvdy
Nov 23 17:38:31 ip-10-0-1-123 kernel: [605949.783777] blkfront: xvdu: barrier or flush: disabled; persistent grants: enabled; indirect descriptors: enabled;
Nov 23 17:38:31 ip-10-0-1-123 kernel: [605949.839874] xvdu: unknown partition table
Nov 23 17:38:32 ip-10-0-1-123 kernel: [605950.260981] btrfs: device label BtrFcdData devid 3 transid 616951 /dev/xvdu
Nov 23 17:38:32 ip-10-0-1-123 kernel: [605950.263252] btrfs: device label BtrFcdData devid 3 transid 616951 /dev/xvdu
Nov 23 17:38:33 ip-10-0-1-123 kernel: [605951.590060] blkfront: xvdo: barrier or flush: disabled; persistent grants: enabled; indirect descriptors: enabled;
Nov 23 17:38:33 ip-10-0-1-123 kernel: [605951.662633] xvdo: unknown partition table
Nov 23 17:38:33 ip-10-0-1-123 kernel: [605951.950477] btrfs: device label BtrFcdData devid 4 transid 616951 /dev/xvdo
Nov 23 17:38:33 ip-10-0-1-123 kernel: [605951.953476] btrfs: device label BtrFcdData devid 4 transid 616951 /dev/xvdo
Nov 23 17:38:35 ip-10-0-1-123 kernel: [605953.098657] btrfs: device label BtrFcdData devid 1 transid 616951 /dev/xvdt
Nov 23 17:38:35 ip-10-0-1-123 kernel: [605953.099002] btrfs: device label BtrFcdData devid 2 transid 616951 /dev/xvdy
Nov 23 17:38:35 ip-10-0-1-123 kernel: [605953.099292] btrfs: device label BtrFcdData devid 3 transid 616951 /dev/xvdu
Nov 23 17:38:35 ip-10-0-1-123 kernel: [605953.099723] btrfs: device label BtrFcdData devid 4 transid 616951 /dev/xvdo
Nov 23 17:38:35 ip-10-0-1-123 kernel: [605953.135590] btrfs: device label BtrFcdData devid 4 transid 616951 /dev/xvdo
Nov 23 17:38:35 ip-10-0-1-123 kernel: [605953.137944] btrfs: disabling disk space caching
Nov 23 17:38:35 ip-10-0-1-123 kernel: [605953.137948] btrfs: force clearing of disk cache
Nov 23 17:38:36 ip-10-0-1-123 kernel: [605954.947400] btrfs: device label BtrFcdData devid 4 transid 616951 /dev/xvdo
Nov 23 17:41:22 ip-10-0-1-123 kernel: [606120.868106] INFO: task mount:12477 blocked for more than 120 seconds.
Nov 23 17:41:22 ip-10-0-1-123 kernel: [606120.871838] Not tainted 3.13.0-92-generic #139-Ubuntu
Nov 23 17:41:22 ip-10-0-1-123 kernel: [606120.874879] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
Nov 23 17:41:22 ip-10-0-1-123 kernel: [606120.878538] mount D ffff88020fc13180 0 12477 7218 0x00000000
Nov 23 17:41:22 ip-10-0-1-123 kernel: [606120.878543] ffff88016d32bc18 0000000000000086 ffff88009bb8e000 0000000000013180
Nov 23 17:41:22 ip-10-0-1-123 kernel: [606120.878547] ffff88016d32bfd8 0000000000013180 ffff88009bb8e000 ffff88009bb8e000
Nov 23 17:41:22 ip-10-0-1-123 kernel: [606120.878550] ffff8800776ca870 ffff8800776ca878 ffffffff00000000 ffff8800776ca880
Nov 23 17:41:22 ip-10-0-1-123 kernel: [606120.878553] Call Trace:
Nov 23 17:41:22 ip-10-0-1-123 kernel: [606120.878562] [<ffffffff8172e2e9>] schedule+0x29/0x70
Nov 23 17:41:22 ip-10-0-1-123 kernel: [606120.878566] [<ffffffff81730f05>] rwsem_down_write_failed+0x115/0x230
Nov 23 17:41:22 ip-10-0-1-123 kernel: [606120.878571] [<ffffffff811dd0eb>] ? iput+0x3b/0x180
Nov 23 17:41:22 ip-10-0-1-123 kernel: [606120.878579] [<ffffffffa00b0000>] ? 0xffffffffa00affff
Nov 23 17:41:22 ip-10-0-1-123 kernel: [606120.878584] [<ffffffff81377da3>] call_rwsem_down_write_failed+0x13/0x20
Nov 23 17:41:22 ip-10-0-1-123 kernel: [606120.878602] [<ffffffffa00b51fa>] ? btrfs_mount+0x2ea/0x800 [btrfs]
Nov 23 17:41:22 ip-10-0-1-123 kernel: [606120.878605] [<ffffffff8173093d>] ? down_write+0x2d/0x30
Nov 23 17:41:22 ip-10-0-1-123 kernel: [606120.878609] [<ffffffff811c3c7e>] grab_super+0x2e/0xa0
Nov 23 17:41:22 ip-10-0-1-123 kernel: [606120.878611] [<ffffffff811c42f0>] sget+0x2d0/0x400
Nov 23 17:41:22 ip-10-0-1-123 kernel: [606120.878621] [<ffffffffa00b29a0>] ? btrfs_parse_early_options+0x1b0/0x1b0 [btrfs]
Nov 23 17:41:22 ip-10-0-1-123 kernel: [606120.878630] [<ffffffffa00b5328>] btrfs_mount+0x418/0x800 [btrfs]
Nov 23 17:41:22 ip-10-0-1-123 kernel: [606120.878634] [<ffffffff811735aa>] ? pcpu_alloc+0x6ca/0xa50
Nov 23 17:41:22 ip-10-0-1-123 kernel: [606120.878637] [<ffffffff8119ad33>] ? alloc_pages_current+0xa3/0x160
Nov 23 17:41:22 ip-10-0-1-123 kernel: [606120.878641] [<ffffffff811c5149>] mount_fs+0x39/0x1b0
Nov 23 17:41:22 ip-10-0-1-123 kernel: [606120.878644] [<ffffffff811e0917>] vfs_kern_mount+0x67/0x110
Nov 23 17:41:22 ip-10-0-1-123 kernel: [606120.878648] [<ffffffff811e31ef>] do_mount+0x25f/0xcd0
Nov 23 17:41:22 ip-10-0-1-123 kernel: [606120.878652] [<ffffffff81156dae>] ? __get_free_pages+0xe/0x50
Nov 23 17:41:22 ip-10-0-1-123 kernel: [606120.878655] [<ffffffff811e2e16>] ? copy_mount_options+0x36/0x170
Nov 23 17:41:22 ip-10-0-1-123 kernel: [606120.878658] [<ffffffff811e3f53>] SyS_mount+0x83/0xc0
Nov 23 17:41:22 ip-10-0-1-123 kernel: [606120.878662] [<ffffffff8173a9dd>] system_call_fastpath+0x1a/0x1f
Se você deseja montar um sistema de arquivos com vários dispositivos usando um dispositivo de loopback, não é suficiente usar o loop mount -o. Em vez disso, você terá que configurar os loopbacks manualmente: