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Zacay
Tux's lil' helper
Joined: 23 Mar 2003
Posts: 95
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 Posted: Fri Nov 19, 2004 3:00 pm Post subject: My raid performance the same as my single drives alone? |
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Hello,
I have a problem with my raid setup.
I have two Raptor 36gb disc setup in Software RAID1.
And when I test my harddrives performance I don't get any speedup at all..
| Code: |
# hdparm -tT /dev/sda /dev/sdb /dev/md3
/dev/sda:
Timing cached reads: 3880 MB in 2.00 seconds = 1939.33 MB/sec
Timing buffered disk reads: 164 MB in 3.00 seconds = 54.62 MB/sec
/dev/sdb:
Timing cached reads: 3868 MB in 2.00 seconds = 1935.26 MB/sec
Timing buffered disk reads: 122 MB in 3.00 seconds = 40.61 MB/sec
/dev/md3:
Timing cached reads: 3812 MB in 2.00 seconds = 1906.29 MB/sec
Timing buffered disk reads: 140 MB in 3.01 seconds = 46.44 MB/sec
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First of I dont' know why my sdb always gets a bit slower, second of all is that my raid setup isn't faster then my single drives alone.
I really need help to solve this, I use this computer as a productionserver.
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Sgaduuw
Tux's lil' helper
Joined: 17 Sep 2002
Posts: 133
Location: Rotterdam, Netherlands
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| Posted: Fri Nov 19, 2004 3:27 pm Post subject: |
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software raid1 doen't make things faster, you just get your data mirrored.
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Zacay
Tux's lil' helper
Joined: 23 Mar 2003
Posts: 95
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transienteagle
Apprentice
Joined: 24 Dec 2003
Posts: 190
Location: UK
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| Posted: Fri Nov 19, 2004 4:02 pm Post subject: |
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Zacay,
You should begin to see a reasonable performance increase (albeit not staggering) on reads from your array in a production environment. I dont believe that hdparm will show this performance gain.
As Sgaduuw said all you are doing with Raid 1 is protecting your data in the event of a system crash (hard disk failure), any performance improvements are a bonus.
Write performance will be slightly downgraded (in theory at least, I would be hard pressed to say that I have noticed any difference)
rgds
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