Messages in this thread | | | Date | Fri, 6 Jul 2007 03:18:40 -0700 (PDT) | From | Martin Knoblauch <> | Subject | Re: Understanding I/O behaviour |
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>> b) any ideas how to optimize the settings of the /proc/sys/vm/ >> parameters? The documentation is a bit thin here. >> >> >I cant offer any advice there, but is raid-5 really the best choice >for your needs? I would not choose raid-5 for a system that is >regularly performing lots of large writes at the same time, dont >forget that each write can require several reads to recalculate the >partity. > >Does the raid card have much cache ram? >
192 MB, split 50/50 to read write.
>If you can afford to loose some space raid-10 would probably perform >better.
RAID5 most likely is not the best solution and I would not use it if the described use-case was happening all the time. It happens a few times a day and then things go down when all memory is filled with page-cache.
And the same also happens when copying large amountd of data from one NFS mounted FS to another NFS mounted FS. No disk involved there. Memory fills with page-cache until it reaches a ceeling and then for some time responsiveness is really really bad.
I am just now playing with the dirty_* stuff. Maybe it helps.
Cheers Martin
------------------------------------------------------ Martin Knoblauch email: k n o b i AT knobisoft DOT de www: http://www.knobisoft.de - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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