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Xserve raid problems with write but not read
Hey there
I have a Xserve raid with 6 harddrives. They are all striped togehter as one big drive and running in raid 3 mode.
I get normal read speed on the drive but my write speed is only around 0.9mb pr sek.
Last week i fixed it with the verify parity data tool but this morning it sundenly came back.
It has been running fine for almost 8 month before i suddenly got this problem.
My systems is a G5 with fibet channel connection to the Xserve raid.If annyboddy can help please DO SO
Thank You
Thomas, DK -
1 Reply
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I’m surprised that you are using RAID 3. My XServe came stripped as RAID 5. For a time I went with RAID 0 to get the most storage, however I returned to RAID in favor of the fault protection.
According to some quick research your problem might be that you’re running RAID 3 instead of RAID 5. RAID 3 uses a dedicated parity disk which generally acts as a performance bottleneck, especially for random writes, because it must be accessed any time anything is sent to the array. In RAID 5, write performance is improved by using distributed parity across several discs.
Obviously RAID 3 worked for you for a period of time. Perhaps as your RAID’s capacity filled, your write performance may have decreased.
If you can I suggest you back up your critical data and re stripe as RAID 5. Recently I had to re stripe and I bought a Maxtor 1TB drive for less than $600 to backup my data.
I hope this helps.
Lee Berger
http://www.leebergermedia.com
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