NetApp question

Question for those of TE working with NetApp. Is there a reason to disable dedupe when NetApp is leveraging flash cache?

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jibbajabba

I don't see a reason why you would. Flash Cache is read caching only and Dedupe has a small write over-head - can imagine if anything, it improves it, not sure though.

down77

Deduplication sparks the age old space vs performance debate for SAN Arrays. Enabling dedupe will cause a performance hit on your SPs, but the question is how much of a hit? Some vendors (EMC, IBM, etc) do not recommend enabling dedupe in their high end storage arrays since you bought them for pure performance. In the case of IBM, dedupe isn't offered! Take a look at this thread regarding deduplication and performance impact on netapp. What it boils down to is how the overall FAS, V series, E series, etc. box you have is performing.

https://communities.netapp.com/thread/4351

jibbajabba

Bear in mind though, NetApp does not dedupe on the fly, only hashes on the fly - which does have a minimal write over-head.

dave330i

@down,

Thanks for the link. Didn't know about that bit of overhead.

@jibba,

Based on research, the NetApp I'm dealing with is build around flash cache and maximizing flash cache useage using dedupe. Really baffled as to why the NetApp "expert" onsite isn't pushing it.

jibbajabba

Def. Flash Cache and not Flash Pool is it ?

dave330i

jibbajabba wrote: »

Def. Flash Cache and not Flash Pool is it ?

Yup. Read only. No SSD drives.

jibbajabba

Maybe that helps

From: xx [mailto@netapp.com]
Sent: 25 July 2013 10:06
To: Michael
Subject: RE: Dedupe / Flash Cache

Hi Michael,

Without more details it’s difficult to comment on the right or wrong thing to do. However, FlashCache is dedupe aware, and in most cases it’s beneficial to enable dedupe to ensure the maximum number of 4KB blocks reside in the cache.

I hope that helps.
Regards,
K

dave330i

jibbajabba wrote: »

Maybe that helps

I showed him NetApp WP stating dedup is important to maximize flash cache, but he won't listen.

It's really sad when management understands the importance of dedupe, but the SAN "expert" doesn't.

jibbajabba

dave330i wrote: »

I showed him NetApp WP stating dedup is important to maximize flash cache, but he won't listen.

It's really sad when management understands the importance of dedupe, but the SAN "expert" doesn't.

Show him the email I posted and ask him to explain his reasoning as you wish to understand it

They charge like $70-80k per year support for one of those damn things - surely you can demand some explanations