[dm-devel] timestamp for shared snapshot

[devicemapper niko]

On Thu, Feb 17, 2011 at 1:55 AM, Alasdair G Kergon <agk at redhat.com> wrote:

> > > Is it possible to add timestamp and comment for each snapshots ?
>
> Good idea - as a userspace lvm2 feature, yes.
>
> We currently store creation details for each VG.
> I agree we should also store such details for each LV.
> This should be optional, but default to enabled.
> (People short of space can perhaps turn it off, discarding any existing
> details.)
>
> Storing a comment is perhaps an extension to tag support that's been
> discussed,
> to allow longer tags with a wider character set.
>
U mean saving the snapshots  timestamp infomation in VGDA?
It's not good i think. hundreds of snaps may be tagged but not attached
using dmsetup create command.
saving attached snaps infomation in VGDA is more reasonable


> > It should be noted that the above shared snapshot work is unlikely to
> > make it upstream (portions of it likely will, for instance the lvm2
> > userspace changes).  A new shared snapshot implementation is in
> > development.
>
> Different snapshot implementations are optimised for different types of
> usage.
> Each one involves choosing between different trade-offs.  We're unlikely
> ever
> to have one solution that is optimal for everyone.
>
> In that spirit, I hope to be submitting more than one shared snapshot
> implementation upstream, including *both* of the ones referred to in this
> message.  But I want the interfaces used by these implementations to be
> basically compatible so that the same userspace tools can make use of them.
>
> Alasdair
>
>
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