Re: Offline Deduplication for Btrfs

[Gordan Bobic <gordan@bobich.net>]

On 01/05/2011 07:01 PM, Ray Van Dolson wrote:
> On Wed, Jan 05, 2011 at 07:41:13PM +0100, Diego Calleja wrote:
>> On Mi=E9rcoles, 5 de Enero de 2011 18:42:42 Gordan Bobic escribi=F3:
>>> So by doing the hash indexing offline, the total amount of disk I/O
>>> required effectively doubles, and the amount of CPU spent on doing =
the
>>> hashing is in no way reduced.
>>
>> But there are people who might want to avoid temporally the extra co=
st
>> of online dedup, and do it offline when the server load is smaller.
>>
>> In my opinion, both online and offline dedup have valid use cases, a=
nd
>> the best choice is probably implement both.
>
> Question from an end-user.  When we say "offline" deduplication, are =
we
> talking about post-process deduplication (a la what Data ONTAP does
> with their SIS implementation) during which the underlying file syste=
m
> data continues to be available, or a process that needs exclusive
> access ot the blocks to do its job?

I was assuming it was a regular cron-job that grinds away on the disks=20
but doesn't require downtime.

Gordan
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