我正在将数据迁移到LUKS分区.既然操作系统驱动器正在运行LUKS,我试图开始迁移数据驱动器.然后服务器停止响应.
这个LUKS设备已经打开：
cryptsetup luksOpen /dev/sdc data1
这些命令中的任何一个都扼杀了服务器：
pv /dev/zero > /dev/mapper/data1 pv /dev/zero > /dev/sdc
不是立即,但在几秒钟内,服务器变得非常缓慢. I / O阻塞的一切：
root@node51 [~]# ps aux | awk '{if($8~"D"||$8=="STAT"){print $0}}'
USER PID %cpu %MEM VSZ RSS TTY STAT START TIME COMMAND
root 1197 0.0 0.0 0 0 ? D 06:39 0:00 [jbd2/dm-1-8]
root 1687 0.1 0.0 0 0 ? D 11:15 0:12 [kworker/u96:5]
root 13057 2.0 0.0 0 0 ? D 13:10 0:01 [dmcrypt_write]
root 13644 10.9 0.0 7452 784 pts/1 D+ 13:10 0:08 pv /dev/zero
root 14159 0.0 0.0 98256 6836 ? DNs 13:10 0:00 sshd: root [priv]
root 14772 0.0 0.0 29008 92 ? D 13:11 0:00 /usr/sbin/CRON -f
root 14773 0.0 0.0 98256 6748 ? DNs 13:11 0:00 sshd: root [priv]
root 15411 0.0 0.0 98256 6876 ? DNs 13:11 0:00 sshd: root [priv]
root 16009 0.1 0.0 98256 6840 ? DNs 13:11 0:00 sshd: root [priv]
root 16632 0.5 0.0 98256 6892 ? DNs 13:11 0:00 sshd: root [priv]
root 16900 0.0 0.0 5448 356 pts/3 D+ 13:11 0:00 awk {if($8~"D"||$8=="STAT"){print $0}}
root 28553 0.6 0.0 0 0 ? D 12:12 0:21 [txg_sync]
值得注意的是,大约两秒钟,pv报告称它以超过2GiB / s的速度复制数据.这是回写缓存和脏页填满(通过监视/ proc / meminfo找到).
之后,pv记录了正常的200MiB / s写入速度,但在回写高速缓存中仍然领先于2GiB和3GiB.
由于所有I / O阻塞正在进行,服务器负载平均值跳升超过10.00.
中断pv写入测试需要一段时间,因为需要清空回写高速缓存,但在测试中止后,服务器性能恢复正常.
有趣的是,这些命令不会导致服务器滞后：
# Reads from dm-crypt block device pv /dev/mapper/data1 > /dev/zero # Reads from the raw block device pv /dev/sdc > /dev/zero # Writes to a control disk of a different model pv /dev/zero > /dev/sdi # Reads from a control disk pv /dev/sdi > /dev/zero # Writes to a file on a dm-crypt ext4 filesystem on a solid-state drive pv /dev/zero > /tmp/empty # Reads from that same solid-state drive pv /dev/sda > /dev/zero
我有这些问题：
>为什么持续顺序写入此数据磁盘会使服务器变慢？
>在写入特定的一个或几个磁盘时,如何避免阻塞其他磁盘？
>为什么这种硬盘会导致性能问题,但其他驱动器却没有？
我有六个相同型号的磁盘(/ dev / sdc,/ dev / sdd,/ dev / sde,/ dev / sdf,/ dev / sdg和/ dev / sdh)进行加密,它们将具有顺序写入工作负载未来,所以我不希望服务器摆脱这个问题.
附加信息
要闻速览
内核：Linux node51 4.4.0-22-generic#39-Ubuntu SMP 5月5日星期五16:53:32 UTC 2016 x86_64 x86_64 x86_64 GNU / Linux
操作系统：Ubuntu Server 16.04 LTS Xenial Xerus 64-bit
有问题的硬盘：Toshiba PH3500U-1I72
我有六个这样的磁盘,都是健康的,我测试了其中两个,并且两者都经历了服务器范围的I / O性能下降.他们在开始时以200MiB / s的速度读写.
控制(无故障)硬盘：Samsung SP1614C
该磁盘的持续写入速度为50MiB / s.可能是有问题的磁盘太快了吗？
磁盘控制器：Dell PERC H310
两个固态驱动器和六个有问题的硬盘驱动器连接到该控制器,所有这些都直接作为AHCI传递.控制盘连接到主板内置的SATA端口.
I / O调度程序
root@node51 [/tmp]# tail -n +1 /sys/block/sd*/queue/scheduler ==> /sys/block/sda/queue/scheduler <== noop [deadline] cfq ==> /sys/block/sdb/queue/scheduler <== noop [deadline] cfq ==> /sys/block/sdc/queue/scheduler <== [noop] deadline cfq ==> /sys/block/sdd/queue/scheduler <== [noop] deadline cfq ==> /sys/block/sde/queue/scheduler <== [noop] deadline cfq ==> /sys/block/sdf/queue/scheduler <== [noop] deadline cfq ==> /sys/block/sdg/queue/scheduler <== [noop] deadline cfq ==> /sys/block/sdh/queue/scheduler <== [noop] deadline cfq ==> /sys/block/sdi/queue/scheduler <== noop [deadline] cfq
将/ dev / sdc的调度程序从noop更改为deadline没有明显的区别.将调度程序更改为cfq似乎可以稍微减少延迟,但其他磁盘上的I / O操作仍然受到影响.
vm.dirty *内核参数
root@node51 [~]# sysctl -a | grep 'vm.dirty' vm.dirty_background_bytes = 0 vm.dirty_background_ratio = 10 vm.dirty_bytes = 0 vm.dirty_expire_centisecs = 3000 vm.dirty_ratio = 20 vm.dirty_writeback_centisecs = 500 vm.dirtytime_expire_seconds = 43200
检测到缓慢并记录到/ var / log / syslog的示例
ZFS事务组同步：
May 11 19:28:44 node51 kernel: [ 4080.179688] INFO: task txg_sync:3179 blocked for more than 120 seconds. May 11 19:28:44 node51 kernel: [ 4080.179905] Tainted: P O 4.4.0-22-generic #39-Ubuntu May 11 19:28:44 node51 kernel: [ 4080.180110] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. May 11 19:28:44 node51 kernel: [ 4080.180357] txg_sync D ffff88060b68baa8 0 3179 2 0x00000000 May 11 19:28:44 node51 kernel: [ 4080.180362] ffff88060b68baa8 ffff880616a96d00 ffff8806133ea940 ffff880603dc2940 May 11 19:28:44 node51 kernel: [ 4080.180366] ffff88060b68c000 ffff880616ad6d00 7fffffffffffffff ffff88056cb8c508 May 11 19:28:44 node51 kernel: [ 4080.180368] 0000000000000001 ffff88060b68bac0 ffffffff818211f5 0000000000000000 May 11 19:28:44 node51 kernel: [ 4080.180372] Call Trace: May 11 19:28:44 node51 kernel: [ 4080.180381] [<ffffffff818211f5>] schedule+0x35/0x80 May 11 19:28:44 node51 kernel: [ 4080.180385] [<ffffffff81824315>] schedule_timeout+0x1b5/0x270 May 11 19:28:44 node51 kernel: [ 4080.180390] [<ffffffff810abe52>] ? default_wake_function+0x12/0x20 May 11 19:28:44 node51 kernel: [ 4080.180395] [<ffffffff810c33b2>] ? __wake_up_common+0x52/0x90 May 11 19:28:44 node51 kernel: [ 4080.180398] [<ffffffff81820744>] io_schedule_timeout+0xa4/0x110 May 11 19:28:44 node51 kernel: [ 4080.180412] [<ffffffffc05afbec>] cv_wait_common+0xbc/0x140 [spl] May 11 19:28:44 node51 kernel: [ 4080.180416] [<ffffffff810c3a70>] ? wake_atomic_t_function+0x60/0x60 May 11 19:28:44 node51 kernel: [ 4080.180423] [<ffffffffc05afcc8>] __cv_wait_io+0x18/0x20 [spl] May 11 19:28:44 node51 kernel: [ 4080.180487] [<ffffffffc071320e>] zio_wait+0x10e/0x1f0 [zfs] May 11 19:28:44 node51 kernel: [ 4080.180528] [<ffffffffc069ce66>] dsl_pool_sync+0x2c6/0x430 [zfs] May 11 19:28:44 node51 kernel: [ 4080.180573] [<ffffffffc06b85b6>] spa_sync+0x366/0xb30 [zfs] May 11 19:28:44 node51 kernel: [ 4080.180576] [<ffffffff810abe52>] ? default_wake_function+0x12/0x20 May 11 19:28:44 node51 kernel: [ 4080.180623] [<ffffffffc06c9a4a>] txg_sync_thread+0x3ba/0x630 [zfs] May 11 19:28:44 node51 kernel: [ 4080.180669] [<ffffffffc06c9690>] ? txg_delay+0x180/0x180 [zfs] May 11 19:28:44 node51 kernel: [ 4080.180676] [<ffffffffc05aae31>] thread_generic_wrapper+0x71/0x80 [spl] May 11 19:28:44 node51 kernel: [ 4080.180682] [<ffffffffc05aadc0>] ? __thread_exit+0x20/0x20 [spl] May 11 19:28:44 node51 kernel: [ 4080.180686] [<ffffffff810a0588>] kthread+0xd8/0xf0 May 11 19:28:44 node51 kernel: [ 4080.180688] [<ffffffff810a04b0>] ? kthread_create_on_node+0x1e0/0x1e0 May 11 19:28:44 node51 kernel: [ 4080.180692] [<ffffffff8182568f>] ret_from_fork+0x3f/0x70 May 11 19:28:44 node51 kernel: [ 4080.180694] [<ffffffff810a04b0>] ? kthread_create_on_node+0x1e0/0x1e0
ext4期刊：
May 11 20:46:46 node51 kernel: [ 6000.186474] INFO: task jbd2/dm-2-8:1148 blocked for more than 120 seconds. May 11 20:46:46 node51 kernel: [ 6000.193164] Tainted: P O 4.4.0-22-generic #39-Ubuntu May 11 20:46:46 node51 kernel: [ 6000.199950] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. May 11 20:46:46 node51 kernel: [ 6000.208323] jbd2/dm-2-8 D ffff88060a6e7c98 0 1148 2 0x00000000 May 11 20:46:46 node51 kernel: [ 6000.208330] ffff88060a6e7c98 0000000000000246 ffff8806133eb700 ffff88060b561b80 May 11 20:46:46 node51 kernel: [ 6000.208333] ffff88060a6e8000 ffff88060aeb68b8 ffff88060a6e7d88 ffff88060a6e7d70 May 11 20:46:46 node51 kernel: [ 6000.208336] ffff88060b561b80 ffff88060a6e7cb0 ffffffff818211f5 ffff8805fd6af900 May 11 20:46:46 node51 kernel: [ 6000.208339] Call Trace: May 11 20:46:46 node51 kernel: [ 6000.208355] [<ffffffff818211f5>] schedule+0x35/0x80 May 11 20:46:46 node51 kernel: [ 6000.208361] [<ffffffff812ea0e0>] jbd2_journal_commit_transaction+0x240/0x1870 May 11 20:46:46 node51 kernel: [ 6000.208365] [<ffffffff810b6be1>] ? dequeue_entity+0x431/0xa80 May 11 20:46:46 node51 kernel: [ 6000.208368] [<ffffffff810b774a>] ? dequeue_task_fair+0x51a/0x8a0 May 11 20:46:46 node51 kernel: [ 6000.208372] [<ffffffff810c3a70>] ? wake_atomic_t_function+0x60/0x60 May 11 20:46:46 node51 kernel: [ 6000.208378] [<ffffffff810ec5fe>] ? try_to_del_timer_sync+0x5e/0x90 May 11 20:46:46 node51 kernel: [ 6000.208381] [<ffffffff812ef32a>] kjournald2+0xca/0x250 May 11 20:46:46 node51 kernel: [ 6000.208384] [<ffffffff810c3a70>] ? wake_atomic_t_function+0x60/0x60 May 11 20:46:46 node51 kernel: [ 6000.208387] [<ffffffff812ef260>] ? commit_timeout+0x10/0x10 May 11 20:46:46 node51 kernel: [ 6000.208391] [<ffffffff810a0588>] kthread+0xd8/0xf0 May 11 20:46:46 node51 kernel: [ 6000.208394] [<ffffffff810a04b0>] ? kthread_create_on_node+0x1e0/0x1e0 May 11 20:46:46 node51 kernel: [ 6000.208397] [<ffffffff8182568f>] ret_from_fork+0x3f/0x70 May 11 20:46:46 node51 kernel: [ 6000.208399] [<ffffffff810a04b0>] ? kthread_create_on_node+0x1e0/0x1e0 May 11 20:46:46 node51 kernel: [ 6292.776357] perf interrupt took too long (2539 > 2500),lowering kernel.perf_event_max_sample_rate to 50000
