On 05/11/2013 08:42 AM, Tim Mohlmann wrote: > Each OSD server uses 4U and can take 36x3.5" drives. So in 36U I can put > 36/4=9 OSD servers, containing 9*36=324 HDDs. SuperMicro has a new 4U chassis w/ 72x3.5" drives (2/canister). You can double the number of drives. (With faster drives you may be getting close to chocking the expander backplane, though.) > HARD DISK DRIVES > > I have been looking for WD digital RE and RED series. RE is more expensive per > GB, but has a larger MTBF and offers a 4TB model. RED is (real) cheap per GB, > but only goes as far a 3TB. WD 3+TB drives don't have the option to turn off "advanced format" or whatever it's called: the part where they lie to the OS about sector size because they ran out of bits for some other counter (will they ever learn). In my tests iostat shows 10x i/o wait on "desktop" wd drives compared to seagates. Aligning partitions to 4096, 16384, or any other sector boundary didn't seem to make any difference. So we quit buying wds. Consider seagates, they go to 4TB in both "enterprise" and desktop lines, too. HTH -- Dimitri Maziuk Programmer/sysadmin BioMagResBank, UW-Madison -- http://www.bmrb.wisc.edu
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