Re: How git affects kernel.org performance

[Jan Engelhardt]

On Jan 7 2007 10:03, Willy Tarreau wrote:
>On Sun, Jan 07, 2007 at 12:58:38AM -0800, H. Peter Anvin wrote:
>> >[..]
>> >entries in directories with millions of files on disk. I'm not
>> >certain it would be that easy to try other filesystems on
>> >kernel.org though :-/
>> 
>> Changing filesystems would mean about a week of downtime for a server. 
>> It's painful, but it's doable; however, if we get a traffic spike during 
>> that time it'll hurt like hell.

Then make sure noone releases a kernel ;-)

>> However, if there is credible reasons to believe XFS will help, I'd be 
>> inclined to try it out.
>
>Hmmm I'm thinking about something very dirty : would it be possible
>to reduce the current FS size to get more space to create another
>FS ? Supposing you create a XX GB/TB XFS after the current ext3,
>you would be able to mount it in some directories with --bind and
>slowly switch some parts to it. The problem with this approach is
>that it will never be 100% converted, but as an experiment it might
>be worth it, no ?

Much better: rsync from /oldfs to /newfs, stop all ftp uploads, rsync
again to catch any new files that have been added until the ftp
upload was closed, then do _one_ (technically two) mountpoint moves
(as opposed to Willy's idea of "some directories") in a mere second
along the lines of

  mount --move /oldfs /older; mount --move /newfs /oldfs.

let old transfers that still use files in /older complete (lsof or
fuser -m), then disconnect the old volume. In case /newfs (now
/oldfs) is a volume you borrowed from someone and need to return it,
well, I guess you need to rsync back somehow.


	-`J'
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