Redundant NFS storage setup (part 3) : The disappointingPERC5/E(solved?)

[Paul M. Dyer]

great article.  But just one followup question:

Shouldn't the starting sector be 127, since sector 0 is the first, and default sector 63 is the 64th??

Paul

----- Original Message -----
From: "Harald Jensas" <Harald_Jensas at dell.com>
To: klandreth at theplanet.com, linux-poweredge at lists.us.dell.com
Sent: Thursday, January 3, 2008 1:04:14 PM (GMT-0600) America/Chicago
Subject: RE: Redundant NFS storage setup (part 3) : The disappointingPERC5/E(solved?)

Kevin, Did you ever try to create your Hardware RAID striped partitions aligned? 
This will cause less stripe crossings and thus less parity to calculate for RAID 5 writes. It should also improve read performance.

In this article they report up to 30% performance increase, in their tests, with properly aligned partitions.
http://insights.oetiker.ch/linux/raidoptimization.html

Assuming block size is 512 bytes.
If Stripe Size is (64KB/512 byte = 128 Blocks) align the partition to block 128.
If Stripe Size is (128KB/512 byte = 256 Blocks) align the partition to block 256.

1. Enter fdisk /dev/sd<x> where <x> is the device suffix.
2. Determine if any partitions already exist.
3. Type n to create a new partition.
4. Type p to create a primary partition.
5. Type 1 to create partition No. 1.
6. Select the defaults to use the complete disk.
7. Type t to set the partition's system ID.
8. Type in the code for the partition type you want.
9. Type x to go into expert mode.
10. Type b to adjust the starting block number.
11. Type 1 to choose partition 1.
12. Type 128 to set it to 128 (the array's stripe element size).
13. Type w to write label and partition information to disk.



--
Harald Jensås

> -----Original Message-----
> From: linux-poweredge-bounces at dell.com [mailto:linux-poweredge-
> bounces at dell.com] On Behalf Of Landreth, Kevin
> Sent: 03 January 2008 17:40
> To: linux-poweredge-Lists
> Subject: RE: Redundant NFS storage setup (part 3) : The
> disappointingPERC5/E(solved?)
> 
> Using setra won't help with writes IIRC.  Has write performance seen
> any
> difference?  In the applications where I use a Perc5 card, writes are
> my
> biggest performance problem and I'd like to see if you write
> performance
> is still suffering.  Using setra will help with software raid just the
> same too I believe so I wouldn't write your problem off as "solved"
> just
> yet.
> 
> Also, could you try ext3 with -E stride=32 (for 128K) and stride=16
> (for
> 64K) and see if you still have the performance issues you had before.
> I
> know this may not be ideal for your application but testing with two
> file systems provides better conclusive answers for everyone beyond a
> reasonable doubt.
> 
> Thanks for all the testing, this is really useful data you are
> providing
> everyone.
> 
> --
> Thanks,
> Kevin Landreth, RHCE
> Technology Architect
> 
> 
> -----Original Message-----
> From: linux-poweredge-bounces at dell.com
> [mailto:linux-poweredge-bounces at dell.com] On Behalf Of Matthias Saou
> Sent: Thursday, January 03, 2008 9:46 AM
> To: linux-poweredge at dell.com
> Subject: Re: Redundant NFS storage setup (part 3) : The
> disappointingPERC5/E (solved?)
> 
> Hi all,
> 
> Looking for information on XFS filesystem options, I found this very
> instructive thread :
> 
> http://oss.sgi.com/archives/xfs/2007-09/msg00322.html
> 
> I read about this simple change in one of the posts, which improved
> performance a lot for the person making the benchmark, so I ran it :
> # blockdev --setra 16384 /dev/sdb
> 
> I now get 500-520MB/s read speed with hardware RAID5 where I used to
> get 30-35MB/s... pretty amazing, I must admit.
> 
> Looking at the man page, this just sets a read-ahead value... I'm
> puzzled yet very happy!
> 
> Would any of the others who reported slow read speeds with their PERC5s
> and MD1000s care to also try it and report back to the list?
> 
> I'll continue digging, but in the meantime, it seems like my "problem"
> might be solved.
> 
> Matthias
> 
> --
> Clean custom Red Hat Linux rpm packages : http://freshrpms.net/
> Fedora release 8 (Werewolf) - Linux kernel 2.6.23.9-85.fc8
> Load : 0.50 0.65 1.03
> 
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