[Sheepdog] Drive snapshots and metadata

[MORITA Kazutaka]

On Mon, Feb 7, 2011 at 7:42 PM, Chris Webb <chris at arachsys.com> wrote:
>> > In an ideal world, it would be good to have some sort of
>> > no-clobber/exclusive mechanism too. For example:
>> >
>> >   $ collie vdi setdata [key] [value] exclusive
>> >
>> > which if [key] is unset, sets it to value [value], or if it is set, fails
>> > with non-zero exit code. (This could be used by a management layer to
>> > implement exclusive access to drives, for example.)
>>
>> Yes, it would be useful to have the feature.
>
> Perhaps a -x argument to specify exclusive/no-clobber behaviour, so the
> final syntax might be
>
>  $ collie vdi getattr KEY
>  $ collie vdi setattr KEY [-x] < VALUEFILE
>  $ collie vdi setattr KEY [-x] VALUE
>  $ collie vdi setattr KEY -d
>
> with getattr returning the value on STDOUT and exit status 0, or exit status
> != 0 if the key doesn't exist, and setattr returning exit status != 0 if the
> key does exist and -x is given.

Looks good to me.  I'll implement those soon. :-)

Thanks,

Kazutaka