[linux-lvm] Performance problem.
spam at tnonline.net
Mon Nov 17 12:45:02 UTC 2003
>> No, that is true. Your low read speed does indicate that you are
>> not using DMA. Give us the output of "hdparm /dev/hda". Also a
>> simple benchmark is to do "dd_rescue /dev/hda /dev/null". What does
>> that give you in numbers?
> multcount = 16 (on)
> IO_support = 1 (32-bit)
> unmaskirq = 0 (off)
> using_dma = 1 (on)
> keepsettings = 0 (off)
> readonly = 0 (off)
> readahead = 8 (on)
> geometry = 14589/255/63, sectors = 234375000, start = 0
This looks good. You could try -c3 to enable 32-bit w/sync and also
enable Write cache -W1 (this may and many not be wise in case you
have power failures often).
> the cables are new (I thought that they may be a problem), I've
> gotten far better speeds on the same system and a worse system
> before I used lvm on the same drives. I REALLY doubt there's
> something wrong with the drives (I replaced one of them because of
> an error, and looked for trouble after replacing that one, but
> didn't find anything else).
> And that dd_rescue will read from /dev/hda and write to /dev/null
> right? Meaning it's a read test, and not a write test (= I won't
> loose any data on it ;) ).
Yes, it is a read-only test! Read the manpage to get all flags you
can use with it (such as how big blocks it is to read etc).
> linux-lvm mailing list
> linux-lvm at sistina.com
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
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