Я создаю четыре тома из четырех снимков состояния EBS на AWS. Четыре тома составляют один диск BTRFS с несколькими устройствами. На дисках нет таблиц разделов, т.е. я запустил mkfs.btrfs /dev/xvdf /dev/xvdg и т.п.
Когда я создаю тома, я присоединяю их с помощью инструмента AWS CLI, затем запускаю btrfs device scan /dev/xvd{f,g,h,i}. У устройств есть этикетка, поэтому для их монтажа я бегу (кое-что пробовал) mount -t btrfs -o ro,nospace_cache,clear_cache -L LABEL /tmp/dir. Виснет довольно долго, минут 15-20. Каждое устройство по 2 ТБ.
Когда я смотрю в dmesg, я вижу следующие сообщения. Пока dmesg зависает, в dmesg не отображается никаких дополнительных результатов. Я не знаю, что еще проверить, чтобы узнать, что вызывает это зависание.
[ 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
Редактировать:
Бег watch iostat -dk 2 -x 1 показывает несколько разные числа, сначала он показывал высокую загрузку на первых двух устройствах, а затем показывает это:
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
Это фрагмент системного журнала:
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
Если вы хотите смонтировать файловую систему с несколькими устройствами с помощью устройства обратной связи, недостаточно использовать mount -o loop. Вместо этого вам придется настраивать петли вручную: