Hello Dan,

Yes, it is true that insufficient memory (or SSD for
the L2ARC) can slow writting down, but with
ZFS deduplication + ZFS compression both turned
on, in production environments we are seeing
deduplication ratios of 12 to 1.  Backup speeds
with such deduplication ratios are rather
spectacular.

Best regards,
Kern

On 10/04/2013 04:12 PM, Dan Langille wrote:
> On 2013-10-04 09:33, Radosław Korzeniewski wrote:
>> Hello,
>>
>> 2013/10/4 Dan Langille <dan AT langille DOT org>
>>
>> On 2013-09-27 14:17, Radosław Korzeniewski wrote:
>> Hello,
>>
>> 2013/9/26 BOURGAULT Antoine <antoine.bourgault AT sib DOT fr>
>>
>> Thanks for your answer ... but can you explain what is " aligned
>> volumes" ?
>>
>> http://www.google.com/search?q=bacula+aligned+volumes [1] [1]
>>
>> I don't know, but I think this refers to ZFS, not Bacula.
>>
>> Bacula aligned volumes works well with ZFS or other deduplication
>> solutions like DataDomain, etc.
> Some issues regarding ZFS dedup to keep in mind:
>
> * Dedup will go slowly unless you have enough RAM to hold every hash for
> every block you are deduping
> * Compression, instead of dedup, can result in higher throughput
> (compression and decompression is faster than writing/reading the larger
> amount of data to/from HDD)
> * The OpenZFS (http://open-zfs.org/) project holds good potential for
> ZFS on Linux
>


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