Networker

Re: [Networker] RHEL6/XFS/NW 7.6.2

2011-11-02 14:37:07
Subject: Re: [Networker] RHEL6/XFS/NW 7.6.2
From: Eugene Vilensky <evilensky AT GMAIL DOT COM>
To: NETWORKER AT LISTSERV.TEMPLE DOT EDU
Date: Wed, 2 Nov 2011 13:32:55 -0500
On Wed, Nov 2, 2011 at 6:55 AM, Francis Swasey <Frank.Swasey AT uvm DOT edu> 
wrote:
>
> I am a firm believer in teach vs give (as in fish...) - So, if you don't 
> mind, would you care to explain why you chose to use those mount/mkfs 
> options?  Perhaps there is some documentation that I have missed in my 
> various searches.

Disclaimer: some of this came from a Gentoo guide / and Google, only
later referenced to man pages. And some might remain
unconfirmed...this is all on a UPS-protected DAS with BBU-protected
cache.
>
> file system mount options:
> rw,noatime,nodiratime,logbufs=8,logbsize=256K,nobarrier,osyncisdsync,inode64

The maximum number of log buffers and their max size to keep in ram,
general explanation is this allows delays between journal commits so
fewer IO for journal updates.

>
> create options:
> mkfs.xfs -l version-2 -d su=128k,sw=11

to match raid stripe size and the number of RAID bands in the device
(22 disks, RAID1+0, 11 bands), with 128K raid stripe
>
> At boot:
> elevator=noop

Don't let the scheduler muck with IO write ordering since there is
cache and limited intelligence on the DAS to take of such things.

>
> and a sizeable read-ahead for sequential reads (with read-ahead completely 
> disabled on the RAID controller itself):
> /sbin/blockdev --setra 16384 /dev/sdxx

 The block device should be smarter than "Adaptive read ahead" or
other hardware read-ahead options.  dd benchmarking (non scientific)
agrees.

Hope this helps.  This is my first large XFS device but so far so
good.  I also aligned the LVM metadata to stripe size with

pvcreate --metadatasize=128KB /dev/sdb --dataalignment=128KB

and am not using partitions on the device.  Otherwise I'd start my
partition on a 128K stripe boundary also.

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