[BBLISA] Fileserver opinion

[Ian Stokes-Rees]

> 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
ijstokes at hkl.hms.harvard.edu               T: +1 617 432-5608 x75
NEBioGrid, Harvard Medical School          C: +1 617 331-5993

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