On Sat, Jan 19, 2002 at 05:58:19PM -0500, Steve Snyder wrote:
> I notice that you (and the original poster) make no mention of network
> interfaces. Are you using gigabit Ethernet or will a 100Mbps interface
> do the job with this much traffic?
100Mbit full duplex copes easily. 220*6k (average object size) makes for
around 10Mbit/sec bandwidth utilisation, so even with the inherent
burstiness of traffic there's plenty of headroom.
> Also, how many SCSI controllers are you using for these 7 10kpm drives?
> Assuming a STR of 52MB/sec (which is about what a Atlas 10K III gets on
> the outer cylinders), it would only take 3 drives to saturate a UW160
> interface. Even a UW320 controller would be inadequate to support the 7
> drives you've mentioned.
This shouldn't really be a problem: the limiting factor on bandwidth is
more likely to be in software than on the disk channels. If network
utilisation is 10Mbit/sec then you'll be using a similar amount of disk
bandwidth. Seek times might have more of an influence on performance, but
that's what the multiple spindles are for.
Our Dell Poweredge 2500 servers come by default with two onboard
controllers, permitting up to six main bay disks split 3+3 or 8 disks (2
extra in the "media bay") split 6+2. While the latter is almost certainly
fine, adding a PCI SCSI controller is relatively inexpensive and so we've
gone for a split across three channels.
The major battle is trying to persuade Dell that we really want to do this,
we've had great trouble on two successive orders...
-- --------------- Robin Stevens <robin.stevens@oucs.ox.ac.uk> ----------------- Oxford University Computing Services ----------- Web: http://www.cynic.org.uk/ ------- (+44)(0)1865: 273212 (work) 273275 (fax) Mobile: 07776 235326 -------Received on Sun Jan 20 2002 - 06:40:05 MST
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