Re: глупый вопрос про RAID
В Чтв, 06/12/2007 в 21:36 +0300, Yuri Kozlov пишет:
> 2007/12/5, Timur S. Sattarov <tumyp@uzsci.net>:
> > При этом информацию от SMART я получить не могу:
> >
> > # smartctl --all /dev/sda
> > smartctl version 5.36 [i686-pc-linux-gnu] Copyright (C) 2002-6 Bruce Allen
> > Home page is http://smartmontools.sourceforge.net/
> >
> > Device: ATA ST3120026AS Version: 8.05
> > Serial number: 3JT3RP2B
> > Device type: disk
> > Device does not support SMART
>
> запусти как
> smartctl -d ata --all /dev/sda
>
> Кстати у меня похожий винт и raid1.
> Model=ST3120026AS , FwRev=3.18
> Model=ST3120813AS , FwRev=3.AAH
> Дают
> $ sudo hdparm -tT --direct /dev/sda /dev/sdb /dev/md0
>
> /dev/sda:
> Timing O_DIRECT cached reads: 96 MB in 2.00 seconds = 47.99 MB/sec
> Timing O_DIRECT disk reads: 166 MB in 3.03 seconds = 54.83 MB/sec
>
> /dev/sdb:
> Timing O_DIRECT cached reads: 260 MB in 2.01 seconds = 129.65 MB/sec
> Timing O_DIRECT disk reads: 166 MB in 3.01 seconds = 55.07 MB/sec
>
> /dev/md0:
> Timing O_DIRECT cached reads: 80 MB in 2.00 seconds = 40.00 MB/sec
> Timing O_DIRECT disk reads: 172 MB in 3.02 seconds = 56.87 MB/sec
>
> То есть в рейде чуть быстрее.
У меня в рейд 10 так:
-------------------------------
# hdparm -Tt /dev/sdb /dev/sdc /dev/sdd /dev/sde /dev/md0
/dev/sdb:
Timing cached reads: 2516 MB in 2.00 seconds = 1258.57 MB/sec
Timing buffered disk reads: 182 MB in 3.03 seconds = 60.07 MB/sec
/dev/sdc:
Timing cached reads: 2402 MB in 2.00 seconds = 1201.08 MB/sec
Timing buffered disk reads: 182 MB in 3.01 seconds = 60.40 MB/sec
/dev/sdd:
Timing cached reads: 2394 MB in 2.00 seconds = 1196.85 MB/sec
Timing buffered disk reads: 184 MB in 3.01 seconds = 61.12 MB/sec
/dev/sde:
Timing cached reads: 2424 MB in 2.00 seconds = 1212.54 MB/sec
Timing buffered disk reads: 176 MB in 3.03 seconds = 58.10 MB/sec
/dev/md0:
Timing cached reads: 2366 MB in 2.00 seconds = 1182.71 MB/sec
Timing buffered disk reads: 294 MB in 3.00 seconds = 97.92 MB/sec
-------------------------------
-------------------------------
# hdparm -Tt /dev/sdb >a & hdparm -Tt /dev/sdc >b
[1] 8414
[1]+ Done hdparm -Tt /dev/sdb >a
# cat a
/dev/sdb:
Timing cached reads: 1258 MB in 2.00 seconds = 628.90 MB/sec
Timing buffered disk reads: 174 MB in 3.03 seconds = 57.51 MB/sec
# cat b
/dev/sdc:
Timing cached reads: 1260 MB in 2.00 seconds = 630.04 MB/sec
Timing buffered disk reads: 170 MB in 3.00 seconds = 56.60 MB/sec
-------------------------------
-------------------------------
# hdparm -Tt /dev/sdb >a & hdparm -Tt /dev/sdc >b & hdparm -Tt /dev/sdd
>c & hdparm -Tt /dev/sde >d
[1] 8838
[2] 8839
[3] 8840
[1] Done hdparm -Tt /dev/sdb >a
[2]- Done hdparm -Tt /dev/sdc >b
[3]+ Done hdparm -Tt /dev/sdd >c
# cat a b c d
/dev/sdb:
Timing cached reads: 602 MB in 2.01 seconds = 300.03 MB/sec
Timing buffered disk reads: 170 MB in 3.00 seconds = 56.60 MB/sec
/dev/sdc:
Timing cached reads: 666 MB in 2.00 seconds = 333.02 MB/sec
Timing buffered disk reads: 172 MB in 3.01 seconds = 57.08 MB/sec
/dev/sdd:
Timing cached reads: 618 MB in 2.00 seconds = 308.67 MB/sec
Timing buffered disk reads: 160 MB in 3.09 seconds = 51.78 MB/sec
/dev/sde:
Timing cached reads: 628 MB in 2.00 seconds = 313.94 MB/sec
Timing buffered disk reads: 158 MB in 3.07 seconds = 51.45 MB/sec
-------------------------------
Так что винты почти друг другу не мешают, а рейд 10 почти в 2 раза
быстрее одного винта. А вот шина делится, и это логично, но её на ~20
винтов хватит.
Кстати, что интересно, во время теста 4-х винтов одновременно по
показаниям atop 2-х ядерный Xeon максимум был занят на 100% из 200%, при
этом 40% system и 60% iowait.
--
Покотиленко Костик <casper@meteor.dp.ua>
Reply to: