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FAST VP on VNX5300
What is minimum number of 100GB Flash disk for create a raid 6 pool for running FAST VP Tiering pool ?
my case is have 3 x 100GB flash disk , 2 for triering and 1 for hotspare .
45 x 600GB SAS , 3 for hot spare .
dynamox
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August 29th, 2011 04:00
for raid-6 you need at least 4 drives, i would use your 2 drives as FAST Cache
jps00
392 Posts
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August 29th, 2011 05:00
The advice above is correct. Three (3) drives is too few for a Flash drive tier.
That number of drives is more appropriate to a FAST Cache. Most likely you purchased the FAST Cache 'package'.
With SAS drives, it is more capacity efficient to use RAID 5, unless your business priorities require the high-availablity of RAID 6.
In addition, according to Best Practices you are over-provisioning your SAS Hot Spares.
I strongly recommend you read the 'Virtual Pools' and 'Hot Spares' sections of EMC Unified Best Practices for Performance and Availablity: Common Platform and O.E. 31.0. This is call VNX Best Practices. It contains a lot of information you will find very helpful in configuring any type of pool-based storage. VNX Best Practices is available on Powerlink.
vEfc9k4L0Q12462
6 Posts
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August 30th, 2011 06:00
thanks all .
How about to use 2 flash disk and 8 SAS HDD to creat a Raid 1/0 FAST VP ?
jps00
392 Posts
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August 30th, 2011 07:00
Very small pools like you propose are not efficient in-terms of capacity utilization. In addition, their performance does not favorably compare to LUNs on traditional RAID groups. In general, you want to create pools with the largest practical number of drives. With the small number of drives like you propose, traditional RAID groups are recommended.
VNX Best Practices describes the recommended minimum number of drives per pool and how to 'size' a pool in both performance and capacity to meet your workload. Again, its strongly recommended that you read this document before provisioning virtual pools.