Wednesday, January 30, 2013

EMC VNX Flare 32

Last week, we upgraded our EMC VNX array to Flare 32. The entire upgrade process took approximately 6 hours and was non disruptive to the block storage and had a slight outage for the file storage as the control stations were being upgraded. Since we don't use file storage at all, there actually wasn't an impact to production.

There are many new enhancements but the ones that stick out the most to me are:

· Mixed RAID Types in Pools: This feature allows a user to define RAID types per storage tier in pool, rather than requiring a single RAID type across all drives in a single pool.


· Rebalance when adding drives to Pools: This feature provides for the redistribution of slices across all drives in a newly expanded pool to improve performance.


· Additional RAID Options in Pools: This feature provides 2 additional RAID options in pools, for better efficiency: 8+1 for RAID 5, and 14+2 for RAID 6. These options will be available for new pools. These options will be available in both the GUI and the CLI.


Full set of changes can be found here:

With the ability to mix RAID types within a pool, we no longer have to waste storage space having to place 600 GB SAS and 1TB+ NLSAS drives all in a RAID6 configuration within a pool. Instead, we can have the 600 GB SAS drives in private RAID5 groups while the 1TB+ NLSAS drives can be kept in RAID6 (as per best practices).

Furthermore, the additional raid options in pools allows for better storage efficiency. If I had a pool of 16 disks that needed to be configured as RAID6, I no longer have to select 2 private raid groups of 6+2, instead giving us the option for a more efficient 14+2 private raid group. However, the tradeoff to this appears to be longer rebuild times so whether you implement it or not depends on your business and environment.

Another thing to note is that previously, when disks are added in order to expand an existing pool, there is no restriping of data slices. Instead, new LUNs created in the pool are only striped across the newest disks, at least until all the disks have the same capacity. LUNs created after that point are then striped across all the disks. In addition, Flare 32 also allows for Fully Automated Storage Tiering (FAST) for private RAID groups within the same tier of disks. We had a few hotspots on our array so this will definitely alleviate the workload on those disks.




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