Re: Two hdds on one channel - why so slow?

Jesse Pollard
2002-01-04T17:41:06Z

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>
> In article <200201041402.IAA80257@tomcat.admin.navo.hpc.mil> you wrote:
> > In my experience, SCSI is not cost effective for systems with a single disk.
> > As soon as you go to 4 or more disks, the throughput of SCSI takes over unless
> > you are expanding a pre-existing workstation configuration.
>
> IDE Scales fine to 8 Channels (aka 8 Drives). Anything more than 8 Drives on
> an HBA is insane anyway.
>
> I love the FC-to-IDE(8) Solution. You get Hardware Raid with 8 Channels, each
> drive a didicated channel, thats much more reliable than usual 2 or 3 channel
> SCSI Configurations.
>
> Do you realy run more than say 10 hard disk devices on a single SCSI Bus,
> ever?

Only place I've seen that (not sure it was true SCSI though) was on a
Cray file server - each target (4) was itself a raid 5, with 5 transports.
That would be total of 20 disks. The four targets were striped together in
software to form a single filesystem. I think that was our first over 300GB
filesystem (several years ago). Now we are using 1 TB to 5TB filesystems
with nearly 5 million files each.

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Jesse I Pollard, II
Email: pollard@navo.hpc.mil

Any opinions expressed are solely my own.