[Lustre-discuss] How to estimate the time for e2fsck on OST

[Andreas Dilger]

On Jul 30, 2009  09:00 +0800, huangql wrote:
> Thanks so much to you. The variables of our filesystem as follow:
> 
> size of the filesystem: 400TB

This cannot be correct, given you have 1.7B 4kB blocks.  Note that
e2fsck time is in parallel on all OSTs.

> number of inodes: 427220992  (set as the default inode size 256)
> number of allocated blocks:1708867323 (set as the default block size 4096)
> distribution of the above on the disk: 4 OSTs on one disk

Putting 4 OSTs on a single disk doesn't make sense.  A single OST
can be up to 8TB, and if you have multiple OSTs on the same disk(s)
it will cause terrible performance problems due to seeking.

> amount of RAM on server: 16GB
> speed of the CPU: Intel(R) Core 8 CPU
> speed of the disks:7200
> 
> Can you give us the more details according to the parameters? And give
> us some suggestions to do e2fsck or make it do faster. We are worried
> about it may destroy the filesystem.
> 
> Thank you in advanced for your help!

Sorry for your misunderstanding, but providing anything more than
a rough estimate of e2fsck time is the best that is possible.  I
would estimate (excluding errors in the filesystem) a 7TB filesystem
would take on the order of 2h or less.

> 
> 发件人： Andreas Dilger 
> 发送时间： 2009-07-29  18:33:13 
> 收件人： huangql 
> 抄送： lustre-discuss 
> 主题： Re: [Lustre-discuss] How to estimate the time for e2fsck on OST 
>  
> On Jul 29, 2009  15:16 +0800, huangql wrote:
> > We want to run e2fsck on OSTs to finish them. However, as to the
> > running time, we should estimate how long it takes to run e2fsck on
> > OSTs. We hopefully to know what elements to affect the running time like
> > the size of OST, the average size of files and so on. Can you give us
> > the tips for it? And I hope to receive you email as soon as possible.
> The variables in your question are numerous:
> - size of the filesystem
> - number of inodes
> - number of allocated blocks
> - distribution of the above on the disk
> - speed of the disks
> - speed of the CPU
> - amount of RAM on server
> Reasonable e2fsck times (without serious filesystem problems) might
> take between 5 minutes and 2 hours.
> Cheers, Andreas
> --
> Andreas Dilger
> Sr. Staff Engineer, Lustre Group
> Sun Microsystems of Canada, Inc.

> _______________________________________________
> Lustre-discuss mailing list
> Lustre-discuss at lists.lustre.org
> http://lists.lustre.org/mailman/listinfo/lustre-discuss


Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.