Device utilization with RAID-1

DISCUSSION Harald Nikolisin 2 participants 3 messages Aug 16, 2011 1 message not in the archive MD RAID

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Harald Nikolisin

author

2011-08-16 00:39 UTC #0 lore raw

Since a long time I'm unhappy with the performance of my RAID-1 system. Investigation with atop and iostat unveils that the disk utilization is always on a certain level although nothing happens on the system. In the case of reading or writing files the utilization boosts always to 100% for a long time. Very ugly examples are "Firefox starting" or "zypper updates".
That is snapshot of the output of iostat:

Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s
avgrq-sz avgqu-sz await svctm %util
sda 0,00 0,00 0,00 7,33 0,00 43,33
5,91 0,33 43,18 33,32 24,43
sdb 0,00 0,00 0,00 7,33 0,00 43,33
5,91 0,35 45,59 39,73 29,13
md0 0,00 0,00 0,00 0,67 0,00 5,33
8,00 0,00 0,00 0,00 0,00

md1               0,00     0,00    0,00    0,33     0,00     5,33   
16,00     0,00    0,00   0,00   0,00
md2               0,00     0,00    0,00    0,33     0,00     1,00

3,00 0,00 0,00 0,00 0,00
md3 0,00 0,00 0,00 0,00 0,00 0,00
0,00 0,00 0,00 0,00 0,00
md4 0,00 0,00 0,00 0,00 0,00 0,00
0,00 0,00 0,00 0,00 0,00
md5 0,00 0,00 0,00 0,33 0,00 0,67
2,00 0,00 0,00 0,00 0,00

I checked with mdadm if a resync happens or so, but this is not the case. The state says "active" on all RAID devices - btw. what is the difference to "clean" ?

thanks for any hints,
harald

Roberto Spadim

2011-08-16 01:30 UTC #1 lore raw

try raid10 with far layout

2011/8/15 Harald Nikolisin <[email protected]>:

Quoted 39 lines

Since a long time I'm unhappy with the performance of my RAID-1 system. Investigation with atop and iostat unveils that the disk utilization is always on a certain level although nothing happens on the system. In the case of reading or writing files the utilization boosts always to 100% for a long time. Very ugly examples are "Firefox starting" or "zypper updates".
That is snapshot of the output of iostat:
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0,00 0,00 0,00 7,33 0,00 43,33 5,91 0,33 43,18 33,32 24,43
sdb 0,00 0,00 0,00 7,33 0,00 43,33 5,91 0,35 45,59 39,73 29,13
md0 0,00 0,00 0,00 0,67 0,00 5,33 8,00 0,00 0,00 0,00 0,00
md1 0,00 0,00 0,00 0,33 0,00 5,33 16,00 0,00 0,00 0,00 0,00
md2 0,00 0,00 0,00 0,33 0,00 1,00 3,00 0,00 0,00 0,00 0,00
md3 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00
md4 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00
md5 0,00 0,00 0,00 0,33 0,00 0,67 2,00 0,00 0,00 0,00 0,00
I checked with mdadm if a resync happens or so, but this is not the case. The state says "active" on all RAID devices - btw. what is the difference to "clean" ?
thanks for any hints,
harald
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Roberto Spadim
Spadim Technology / SPAEmpresarial
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Harald Nikolisin

author

2011-08-16 17:25 UTC #3 lore raw

well, I have only 2 hard drives and no space for more..

Am 16.08.2011 03:29, schrieb Roberto Spadim:

Quoted 51 lines

try raid10 far layout

2011/8/15 Harald Nikolisin <[email protected]
<mailto:[email protected]>>

    Since a long time I'm unhappy with the performance of my RAID-1 system.
    Investigation with atop and iostat unveils that the disk utilization is
    always on a certain level although nothing happens on the system. In the
    case of reading or writing files the utilization boosts always to 100%
    for a long time. Very ugly examples are "Firefox starting" or "zypper
    updates".
    That is snapshot of the output of iostat:


    Device:         rrqm/s   wrqm/s     r/s     w/s   rsec/s   wsec/s
    avgrq-sz avgqu-sz   await  svctm  %util
    sda               0,00     0,00    0,00    7,33     0,00    43,33
    5,91     0,33   43,18  33,32  24,43
    sdb               0,00     0,00    0,00    7,33     0,00    43,33
    5,91     0,35   45,59  39,73  29,13
    md0               0,00     0,00    0,00    0,67     0,00     5,33
    8,00     0,00    0,00   0,00   0,00
    md1               0,00     0,00    0,00    0,33     0,00     5,33
    16,00     0,00    0,00   0,00   0,00
    md2               0,00     0,00    0,00    0,33     0,00     1,00
    3,00     0,00    0,00   0,00   0,00
    md3               0,00     0,00    0,00    0,00     0,00     0,00
    0,00     0,00    0,00   0,00   0,00
    md4               0,00     0,00    0,00    0,00     0,00     0,00
    0,00     0,00    0,00   0,00   0,00
    md5               0,00     0,00    0,00    0,33     0,00     0,67
    2,00     0,00    0,00   0,00   0,00

    I checked with mdadm if a resync happens or so, but this is not the
    case. The state says "active" on all RAID devices - btw. what is the
    difference to "clean" ?

    thanks for any hints,
     harald
    --
    To unsubscribe from this list: send the line "unsubscribe linux-raid" in
    the body of a message to [email protected]
    <mailto:[email protected]>
    More majordomo info at  http://vger.kernel.org/majordomo-info.html

Signature · 2 lines

Roberto Spadim
Spadim Technology / SPAEmpresarial