Re: [linux-lvm] performance problems

Re: [linux-lvm] performance problems

[Andreas Dilger]

Chris writes:
> We are using LVM on a (hardware) RAID array and are
> having some performance problems.  File copying is
> very slow and one of the guys using it reported that
> untarring was very sluggish, and he got I/O errors. 
> Is this a known problem?  I believe we are using 0.8i
> and we are using 2.2.13 kernel.  Any help would be
> greatly appreciated.

Have you been using LVM without problem before, or is this a brand new
installation?

If the speed problem is new (i.e. LVM has been installed and working
well for a while), it may well be that you have a disk problem, and the
RAID array is slow because it needs to do extra parity calculations for
all I/O.  Getting I/O errors is a bad sign, as LVM doesn't know anything
about hardware RAID, it only knows there is a big disk beneath it.

If it is a new LVM installation, it may be that you want to check the
RAID stripe size/PE size/ext2 RAID stride are all set to reasonable
multiples of each other for maximum performance.

Cheers, Andreas
-- 
Andreas Dilger  \ "If a man ate a pound of pasta and a pound of antipasto,
                 \  would they cancel out, leaving him still hungry?"
http://www-mddsp.enel.ucalgary.ca/People/adilger/               -- Dogbert

Re: [linux-lvm] performance problems

[Matthew O'Keefe]

Hi,

have you really isolated the problem to LVM?  Is the performance
good without LVM on this particular array?

Matt O'Keefe

On Mon, Jun 05, 2000 at 09:00:16AM -0700, Chris Campbell wrote:
> We are using LVM on a (hardware) RAID array and are
> having some performance problems.  File copying is
> very slow and one of the guys using it reported that
> untarring was very sluggish, and he got I/O errors. 
> Is this a known problem?  I believe we are using 0.8i
> and we are using 2.2.13 kernel.  Any help would be
> greatly appreciated.
> 
> 
> 
> Chris
> 
> __________________________________________________
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Re: [linux-lvm] performance problems

[Paul Jakma]

On Mon, 5 Jun 2000, Chris Campbell wrote:

> We are using LVM on a (hardware) RAID array and are
> having some performance problems.  File copying is
> very slow and one of the guys using it reported that
> untarring was very sluggish, and he got I/O errors. 
> Is this a known problem?  I believe we are using 0.8i
> and we are using 2.2.13 kernel.  Any help would be
> greatly appreciated.

did you specify for any LV's to be contigious?

i've seen something similar where i get I/O errors because (i
suspect) an contigious LV can't find any contigious blocks. (even
though there's plenty of space in the VG.

-- 
Paul Jakma	paul@clubi.ie
PGP5 key: http://www.clubi.ie/jakma/publickey.txt
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[linux-lvm] performance problems

[Chris Campbell]

We are using LVM on a (hardware) RAID array and are
having some performance problems.  File copying is
very slow and one of the guys using it reported that
untarring was very sluggish, and he got I/O errors. 
Is this a known problem?  I believe we are using 0.8i
and we are using 2.2.13 kernel.  Any help would be
greatly appreciated.



Chris

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