[linux-lvm] Snapshot behavior on classic LVM vs ThinLVM

[Gionatan Danti]

Il 04-03-2018 21:53 Zdenek Kabelac ha scritto:
> On the other hand all common filesystem in linux were always written
> to work on a device where the space is simply always there. So all
> core algorithms simple never counted with something like
> 'thin-provisioning' - this is almost 'fine' since thin-provisioning
> should be almost invisible - but the problem starts to be visible on
> this over-provisioned conditions.
> 
> Unfortunately majority of filesystem never really tested well all
> those 'weird' conditions which are suddenly easy to trigger with
> thin-pool, but likely almost never happens on real hdd....

Hi Zdenek, I'm a little confused by that statement.
Sure, it is 100% true for EXT3/4-based filesystem; however, asking on 
XFS mailing list about that, I get the definive answer that XFS was 
adapted to cope well with thin provisioning ages ago. Is it the case?

Anyway, a more direct question: what prevented the device mapper team to 
implement a full-read-only/fail-all-writes target? I feel that *many* 
filesystem problems should be bypassed with full-read-only pools... Am I 
wrong?

Thanks.

-- 
Danti Gionatan
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