> I don't have any advice, but I have a few questions: > > 0) What is the drive interface card? Several cards? Do they do the RAID > support or is that in software?
Adaptec RAID 52445 28-Port (24 Int/4 Ext) (SAS) (SFF-8087) Hardware RAID. One card. > 1) Is it obvious that one needs 12 cores to fill a single GB ethernet > link? Or are there more ethernet links? If more, how do you balance the > load (not a rhetorical question - we have systems with multiple > ethernets and don't have any idea how to use them effectively). Another colleague has already given the very good advice of considering a Dell 6248 switch that has 2 10GigE ports so we'd then get high b/w network access to the file server with the addition of a 10GigE card on the server. > 2) With data spanned over 5 drives, is there still a performance > difference between 7,200 rpm and 15,000 rpm drives? Have you the ability > to experiment before putting out the cash? I don't know. No, we can't test this before purchasing, so any experience on this would be appreciated. Our best guess is that faster is faster, and we need faster, but it is a "best guess", hence the petition to bblisa. > 3) How long do you think it will take to rebuild a volume after a drive > failure? Do you need such large volumes. If the volumes are smaller the > rebuild times are lower. I have no experience with 15,000 rpm SAS > drives, but is the system really usable during a rebuild? Now if the > drives have 500,000 hours mean time to failure, and you have 10, that is > still 5 years mean time to a rebuild, but somehow I don't believe 15,000 > rpm drives are really that durable in real life. Will the system be down > a day a year for RAID rebuilding? Good question. With RAID10 I'd hope that re-buildling can be done in the background with the data "at risk" during that period. We're not in an operational environment where uptime demands are extremely high -- i.e. we're only aiming for >97% uptime (down several days over the course of a year is acceptable). Ian -- Ian Stokes-Rees, PhD W: http://hkl.hms.harvard.edu [email protected] T: +1 617 432-5608 x75 NEBioGrid, Harvard Medical School C: +1 617 331-5993
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