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SSDs, pNFS Will Test RAID Controller Design

Jul 25, 2009, 23:02 (1 Talkback[s])
(Other stories by Henry Newman)

[ Thanks to Paul Shread for this link. ]

"RAID vendors look at me like I'm nuts when I say this. Data storage is an IOPS world, they say, so why should I care about streaming performance? For those of you who don't know, IOPS is the number of I/O requests per second, while streaming bandwidth is how many gigabytes per second the controller can deliver to a server or servers.

"Disk drives can support a limited number of random IOPS, but for flash drives, the number is virtually unlimited. Add parallel NFS to the picture and the number of I/O requests per second won't matter if the controller has relatively poor streaming I/O.

"Common wisdom has held until now that I/O is random. This may have been true for many applications and file system allocation methodologies in the recent past, but with new file system allocation methods, pNFS and most importantly SSDs, the world as we know it is changing fast. RAID storage vendors who say that IOPS are all that matters for their controllers will be wrong within the next 18 months, if they aren't already. Flash-based SSDs, file system design changes and NFSv4.1 (pNFS) will affect everything end-to-end, from high-end arrays to low-end SAS and SATA."

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