Wednesday, May 20, 2009

EFD Specs

There is a large lack of knowledge about Enterprise Flash Drives, what they can do and what they cant. I for one am one of those with minimal knowledge and understanding. This is some of the information I found at EMCWorld.

An EFD is composed of 16 smaller flash chips, managed by an internal processor with onboard cache

Lifespan - We all know that flash drives have a limited lifespan, is that something I should be concerned with? Supposedly, the EFDs can support millions of rewrites without issue, comporable to that of FC drives.

Performance - A conservative number is 2500 IOPs per disk, and 100 MB/s. These are very conservative numbers and could be up to 10x this.

RAID configurations - You still want redundant disks, just as with FC, SAS, or SATA, so what configuration do you use. All RAID types are available (0,1,5,10), and due to the high performance characteristics, RAID5 is generally appropriate.

READ vs. Write - Read for EFD is considerably faster than Write, but writes are still faster than with traditional disks. This can be improved by enabling the SAN write cache, but it is general practice to leave this disabled.

What are you trying to purchase with your disks? This ultimately determines what type of storage is needed.






TypeStorage
SpaceSATA / FC
IOPSEFD
Response TimEFD
ThroughputEFD / FC


Is EFD a silver bullet for your performance issues? Maybe. It will help resolve many hardware wait issues, but wont resolve all the processing performance issues you may have. You should always make sure and validate where the waits are to ensure this will help.

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