Matt Doidge wrote:
> Heya guys,
>
> We're looking to buy more storage and we got quoted the standard
> 24-bay 4-U supermicro chassis BUT filled with 2TB Enterprise disks for
> a very competitive price (VERY competitive. 2/3 of the price of the
> nearest quote for 200TB competive). However common wisdom suggests
> that more then 20TB/box isn't a good idea. We're currently LAN limited
> but this hopefully will be fixed in the near future, so my plan to
> reduce potential bottlenecks if we went for these huge pools would be
> to bond ethernet links out of the boxes to 2Gb internal (farm traffic)
> and 2Gb external(WAN traffic). Does the storage group have any
> opinions on pools >> 20TB is size?
Having been through a similar choice recently my opinion is that there
is a compromise between cost, rack space, performance, and reliability.
Assuming you're aiming for a fixed total amount of storage I would say
the Pros and Cons of the 2TB solution are
Pro
Cheaper (get more storage or kit elsewhere)
Fewer systems equals less rack space/cabling
Fewer drives equals fewer drive failures
Con
Less striping of data files across pools (< aggregate performance)
Reliability of individual arrays is worse (2TB drives take a very long
time to rebuild and more chance of hitting an error)
2TB drives are a lot newer, more chance of teething problems
For us we stuck with the tested 1TB solutions for our next round of
storage as we have (just) enough space to easily accommodate more
systems and even with 3Gbit bonded links to the research LAN it's
already looking like network bandwidth to the pools is going to be a
major bottle neck so the more machines the better (10G NICs would
certainly help but raise the extra infrastructure prices way too high
for us atm).
As storage requirements increase we will go with a 2TB solution
eventually, maybe next year.
John
--
Dr John Bland, Systems Administrator
Room 210, Oliver Lodge
Particle Physics Group, University of Liverpool
Mail: [log in to unmask]
Tel : 0151 794 3396
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