From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ric Wheeler <rwheeler@redhat.com>
Subject: Re: large fs testing
Date: Tue, 26 May 2009 13:47:44 -0400
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Cc: linux-fsdevel@vger.kernel.org,
	Christoph Hellwig <hch@infradead.org>,
	Douglas Shakshober <dshaks@redhat.com>,
	Joshua Giles <jgiles@redhat.com>,
	Valerie Aurora <vaurora@redhat.com>,
	Eric Sandeen <esandeen@redhat.com>,
	Steven Whitehouse <swhiteho@redhat.com>,
	Edward Shishkin <edward@redhat.com>,
	Josef Bacik <jbacik@redhat.com>,
	Jeff Moyer <jmoyer@redhat.com>,
	Chris Mason <chris.mason@oracle.com>,
	"Whitney, Eric" <eric.whitney@hp.com>, Theodore Tso <tytso@mit.edu>
To: nicholas.dokos@hp.com
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On 05/26/2009 01:39 PM, Nick Dokos wrote:
>> (3) FS creation time - can you create a file system in reasonable
>> time? (mkfs.xfs took seconds, mkfs.ext4 took 90 minutes). I think that
>> 90 minutes is definitely on the painful side, but usable for most.
>>
>
> I get better numbers for some reason: on a 32 TiB filesystem (16 LUNs,
> 2TiB each, 128KiB stripes at both the RAID controller and in LVM), using
> the following options, I get:
>
> # time mke2fs -q -t ext4 -O ^resize_inode -E stride=32,stripe-width=512,lazy_itable_init=1 /dev/mapper/bigvg-bigvol
>
> real	1m2.137s
> user	0m58.934s
> sys	0m1.981s
>
>
> Without lazy_itable_init, I get
>
> # time mke2fs -q -t ext4 -O ^resize_inode -E stride=32,stripe-width=512 /dev/mapper/bigvg-bigvol
>
> real	12m54.510s
> user	1m4.786s
> sys	11m44.762s
>
> Thanks,
> Nick

Hi Nick,

These runs were without lazy init, so I would expect to be a little more than 
twice as slow as your second run (not the three times I saw) assuming that it 
scales linearly. This run was with limited DRAM on the box (6GB) and only a 
single HBA, but I am afraid that I did not get any good insight into what was 
the bottleneck during my runs. Also, I am pretty certain that most arrays do 
better with more, smaller sized LUN's (like you had) than fewer, larger ones.

Do you have any access to even larger storage, say the mythical 100TB :-) ? Any 
insight on interesting workloads?

Thanks!

Ric