From: Eric Sandeen <sandeen@sandeen.net>
To: Spelic <spelic@shiftmail.org>, xfs@oss.sgi.com
Subject: Re: XFS shrinking planned?
Date: Wed, 29 Oct 2014 08:03:07 -0500 [thread overview]
Message-ID: <5450E58B.10106@sandeen.net> (raw)
In-Reply-To: <5450B560.6000208@shiftmail.org>
On 10/29/14 4:37 AM, Spelic wrote:
> On 28/10/2014 18:39, Eric Sandeen wrote:
>> Not formally planned, there are bits and pieces out there (i.e. the inode
>> mover) which are part of what it might take to achieve a shrinker.
>>
>> Another option, rather than fs shrinking, is to use the dm-thinp target, which
>> would allow you to allocate a large-but-sparse block device, create a very
>> large filesystem on that, and add or remove storage as needed.
>> (At least I think you can remove it...!)
>>
>> -Eric
>
> Thanks for your reply Eric
>
> Interesting technique, but for enforcing a maximum size (smaller than
> the very large allocated thin device) I would have to rely on quotas,
> which probably decreases performance.
"probably"
> Then using thinp would mess up
> all the disk layout, basically replacing the XFS allocator, which
> most likely would decrease performances significantly.
"most likely"
> And then the
> thinp code itself is a medium performance thing and I don't think it
> can keep up with XFS performances, so that would presumably be a hard
> bottleneck.
"presumably"
> All this would result in a performance almost certainly
> lower than ext4.
"almost certainly..."
All possibilities, but possibly also worth testing to find out. ;)
It's true that today the thinp allocator will impact XFS allocation
patterns to some degree.
Anyway, shrink has been on the radar for years, it's just never really
been a priority. It might happen some day...
-Eric
> Thanks
> S.
>
_______________________________________________
xfs mailing list
xfs@oss.sgi.com
http://oss.sgi.com/mailman/listinfo/xfs
prev parent reply other threads:[~2014-10-29 13:03 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-28 16:19 XFS shrinking planned? Spelic
2014-10-28 17:39 ` Eric Sandeen
2014-10-29 9:37 ` Spelic
2014-10-29 13:03 ` Eric Sandeen [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=5450E58B.10106@sandeen.net \
--to=sandeen@sandeen.net \
--cc=spelic@shiftmail.org \
--cc=xfs@oss.sgi.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.