Re: RBD image name constraints

From: Ilya Dryomov <idryomov@gmail.com>
To: Jason Dillaman <dillaman@redhat.com>
Cc: "Wido den Hollander" <wido@42on.com>,
	"Bartłomiej Święcki" <bartlomiej.swiecki@corp.ovh.com>,
	"Mykola Golub" <mgolub@mirantis.com>,
	"Josh Durgin" <jdurgin@redhat.com>,
	"Ceph Development" <ceph-devel@vger.kernel.org>
Subject: Re: RBD image name constraints
Date: Tue, 12 Apr 2016 15:23:10 +0200	[thread overview]
Message-ID: <CAOi1vP-7Xdcy7SAwuwTbjE=YuQy-toLW_tLXYNDsEnM-sDrB=w@mail.gmail.com> (raw)
In-Reply-To: <842665427.50033069.1460466113899.JavaMail.zimbra@redhat.com>

On Tue, Apr 12, 2016 at 3:01 PM, Jason Dillaman <dillaman@redhat.com> wrote:
>> > Op 12 april 2016 om 14:32 schreef Bartłomiej Święcki
>> > <bartlomiej.swiecki@corp.ovh.com>:
>> >
>> >
>> >
>> > On 04/11/2016 05:08 PM, Ilya Dryomov wrote:
>> > > On Mon, Apr 11, 2016 at 4:29 PM, Jason Dillaman <dillaman@redhat.com>
>> > > wrote:
>> > >
>> > >> It would probably make sense to relax it for non-create operations and
>> > >> use
>> > >> a strict regex for create/clone/import/rename operations.
>> > > I think it would also make sense to start enforcing a limit on the
>> > > length of the image name on create/clone/etc.  I'm not pushing for it
>> > > to be 96 chars (although I do believe it'd be sensible), just that we
>> > > don't want it to be RADOS - strlen("rbd_id.").
>> > >
>> > > Thanks,
>> > >
>> > >                  Ilya
>> > Sounds like a good plan to me, maybe we should also consider allowed
>> > character set? Non-ascii or control characters make little sense here too.
>> >
>>
>> Seems like a sane thing to me:
>>
>> a-z, A-Z, 0-9, -, _ and . are the characters you want to allow in a image's
>> name. I can't think of anything more.
>>
>> Wido
>>
>> > Regards,
>> > Bartek
>> > --
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>
> All of this sounds good to me -- we should circulate a proposal in ceph-users before making any change.  Assuming we can reach a plan that doesn't break someone's Ceph deployment, this could be included as part of the Kraken-release.
>
> Ilya -- just so that I am clear, is the current kernel limitation 96 characters minus the "rbd_id."-prefix (format 2) or ".rbd"-suffix (format 1)?

It's 100 chars for a RADOS object name, including any prefixes and
suffixes.  So 96 chars (matches RBD_MAX_IMAGE_NAME_SIZE) for a format 1
image and 93 chars for a format 2 image.  It's a pity it didn't get
updated when format 2 support got merged...

Thanks,

                Ilya
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