Unsolved
This post is more than 5 years old
5 Practitioner
•
274.2K Posts
0
672
Information around FAST Cache
Hello everyone
I have a customer with a VNX 5300 with 2 200GB SD for FAST cache. I’ve done the SP/NAR collect on the array and presented to the customer already.
Question is is there a way to know HOW the Fast Cache SSD’s are being used by the VNX? If the existing capacity is underutilized, over utilized, etc, or additional capacity is needed. Are there other tools available to get that info ?
My understanding is that since we cannot specifically allocated sections on the fast cache, but just enable them on the pools we don’t control that area right?
I have also looked at the SP/NAR the Fast Cache does look being utilized well. You can add 2 more SSD’s ( to max it out since 4 is the max on a VNX5300). I’ve also seen that they have 5 RAID groups and have FAST Cache enabled on only one of them.
Beyond that, I am not sure what other info I can get. Any help is appreciated. What other options do I have?
Thanks in advance for your help.
sameek
60 Posts
0
July 18th, 2014 08:00
Hi Harish,
Below is the link for white paper which may help you.
https://www.emc.com/collateral/software/white-papers/h8046-clariion-celerra-unified-fast-cache-wp.pdf
Thanks
Sameeksha
adhamakady
65 Posts
1
July 21st, 2014 00:00
Hello,
I would not try to find out how much of the FAST Cache is actually being used; always assume it is pretty much full while enabled (after it has had time to 'warm up').
Instead, try to analyze the read/write hit rate, dirty pages percentage, and how much throughput is on the individual EFDs.
I find Unisphere Analyzer to be quite useful when analyzing FAST Cache performance. This can help:
https://support.emc.com/kb/15606.
Hope this helps,
Adham
Unified Performance Support
Anonymous User
375 Posts
0
July 21st, 2014 01:00
You can try to implement FAST VP and FAST Cache will be much faster to work with the system. Use FAST VP within storage pools.
https://www.ndm.net/emcvnx/pdf/vnx/h8046-clariion-celerra-unified-fast-cache-wp.pdf
Thnx
Rakesh
BrentV21
4 Posts
0
July 29th, 2014 12:00
Harish,
EMC internal TC's and partners with USPEED access have tools that can give visibility inside the Fast Cache at the drive, RG and private LUN levels. This will show if FC is saturated. Do you have a resource at EMC that you could reach out to?
Brent
sk_
104 Posts
0
August 5th, 2014 10:00
I agree, contact EMC reps and they can help with analysis for the FastCache performance.. and also looking at the skew of the workloads, with ktrace and such.
sk