Enterprise SATA/SAS 4 TB Drives Arrive

Enterprise SATA/SAS 4 TB drives are here, in case you had not seen. I am sure that RAID vendors will be soon qualifying the drives, and we will see them in storage controllers in a few months or less, as some vendors might have already started qualification. I have a concern that RAID-6 is not robust enough to deal with the density, given the long rebuild times and the potential for a triple failure. I wrote about this about 2.5 years ago, and I have seen little movement in the industry to support declustered RAID across the industry. I would not be purchasing 4 TB drives from any vendor unless that vendor supported some type of declustering algorithm, as rebuild times with 4 TB drives will increase the likelihood for a triple failure with RAID-6. Do not even consider RAID-5. Of course, you could go to RAID-6 4+2 to reduce the impact, but you are now using 12 drives vs. 10 drives. It kind of defeats the purpose, doesn't it?

If I were purchasing storage, I would either demand that the vendor provide declustered RAID support or say that I will buy its product with only 2 TB drives. Those vendors that support declustered RAID will have a major price advantage. The Hitachi data was not clear on the performance -- it said 171 MB/sec sustained rate. I am not sure if that is 1024*1024 or 1000*1000 and if the 171 is sustained for the whole drive or just a portion of the drive. Anyway, using 1024 and 171 MB/sec for the whole drive (just a guess) it takes more than 6 hours to read the whole drive. That, of course, assumes you are doing nothing else. We as customers need to demand 4 TB drives with declustered RAID.

Labels: disk drives,RAID,SAS,SATA

posted by: Henry Newman

Henry Newman, InfoStor Blogger
by Henry Newman
InfoStor Blogger

Henry Newman is CEO and CTO of Instrumental Inc. and has worked in HPC and large storage environments for 29 years. The outspoken Mr. Newman initially went to school to become a diplomat, but was firmly told during his first year that he might be better suited for a career that didn't require diplomatic skills. Diplomacy's loss was HPC's gain.

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