[OmniOS-discuss] ZFS Dedup

[Guenther Alka]

I have not seen yet how much better dedup2 in Solaris is,
but the current Open-ZFS implementation has the following problems

- You must keep the dedup table in any case in RAM as this is realtime 
dedup
otherwise a pool import or snapshot delete can last ages and performance 
can become unusable slow.

- it requires a lot of RAM that you want to use for cachingand performance.
Depending on data we talk about 1-5 GB RAM / TB dedup data(that is 
required additionally to your cache demands).

- while you can enable on a filesystem level it operates on pool level.
once activated you cannot disable beside a pool destroy.

In the end, it may be a good idea but only when you have enough RAM and 
very high dedup rates (say >5-10)
that are much better then the compress rate with lz4

Mostly the dedup rate is not good enough compared to a larger pool with 
lz4 dedup
where you do not need to care about the dedup restrictions.

gea
@napp-it.org


Am 03.05.2018 um 09:22 schrieb Oliver Weinmann:
>
> Hi,
>
> I always hear people saying don’t use dedup with ZFS. Is that still 
> the case? We use omnios as a VEEAM backup target and I would assume 
> that using dedup would save a lot of disk space.
>
> Best Regards,
>
> Oliver
>
> *Oliver Weinmann*
> Head of Corporate ICT
>
> Telespazio VEGA Deutschland GmbH
> Europaplatz 5 - 64293 Darmstadt - Germany
> Ph: +49 (0)6151 8257 744 | Fax: +49 (0)6151 8257 799
> oliver.weinmann at telespazio-vega.de 
> <mailto:oliver.weinmann at telespazio-vega.de>
> www.telespazio-vega.de
>
> Registered office/Sitz: Darmstadt, Register court/Registergericht: 
> Darmstadt, HRB 89231; Managing Director/Geschäftsführer: Sigmar Keller
>
>
>
> _______________________________________________
> OmniOS-discuss mailing list
> OmniOS-discuss at lists.omniti.com
> http://lists.omniti.com/mailman/listinfo/omnios-discuss

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://omniosce.org/ml-archive/attachments/20180503/e81f9b6d/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Logo_Telespazio_180_px_signature_eng_b58fa623-e26d-4116-9230-766adacfe55e1111111111111.png
Type: image/png
Size: 7535 bytes
Desc: not available
URL: <https://omniosce.org/ml-archive/attachments/20180503/e81f9b6d/attachment.png>