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Re: Linux XFS write performance

To: "Michael Loftis" <mloftis@xxxxxxxxx>
Subject: Re: Linux XFS write performance
From: delusion@xxxxxxxxxxxx
Date: Sun, 17 Apr 2005 16:05:21 -0700 (PDT)
Cc: delusion@xxxxxxxxxxxx, linux-xfs@xxxxxxxxxxx
In-reply-to: <A2122DBD91F7C8AF935D0615@[10.1.2.230]>
References: Your message of "Sun, 17 Apr 2005 00:10:57 EST." <2ca133d205041622106b61c016@mail.gmail.com> <31874.1113718752@ocs3.ocs.com.au><2254.67.49.24.45.1113753740.spork@webmail.delusion.com> <A2122DBD91F7C8AF935D0615@[10.1.2.230]>
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The card is a PCI-X 133 although there is also a PCI-E 8x card.
The PCI-E card uses a PCI-X 133 bus on the card so there shouldn't be 
much of a difference. The card supposedly can do the speeds
but I haven't been able to get

>Could you explain in more details what you have and what you are
doing?

14 x WD raptors (73GB), 3.2GHz dual EMT64, 2GB, Supermicro motherboard.
This is essentially a box that needs to backup data coming
in over infiniband. The data will be written in 16mb files.

>It depends, large streeam O_DIRECT writes to preallocated space is
>probably worth experiementing with.  I would also let mkfs.xfs know
>about the underlying RAID topology and see if that helps.

Thanks. Is opening files on the fly till a bit slow as it used
to be on IRIX? Sounds like preallocating and opening is the best
way to go then? Is there a fast way to preallocate in XFS (my xfs experience
dates back a few years on irix and I need to catch up on what's been done
since then). I did try sunit=256 and swidth=256*14 (I'm not testing raid
5/6
yet) but it didn't seem to help much. I also tried setting both to zero
but it still didn't help.


>600MB/s is a fair amount of bandwidth, you probably need 2x or 3x this
>in the system to achieve this and depending on what you are doing that
>might not even be enough --- more details?

It's a fairly straightforward case... 16MB files all written
sequentially. In this case, would it be better to use one thread
for writing or multiple threads?

Thanks.



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