Messages in this thread | | | Date | Mon, 14 Dec 1998 14:53:18 +0000 (GMT/BST) | From | Mike Jagdis <> | Subject | Re: Dumb question: Which is "better" SCSI or IDE disks? |
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On Sat, 12 Dec 1998, Eric Lee Green wrote:
> On Wed, 9 Dec 1998, Gregory Maxwell wrote: > > What? Join the real world but. Raid-1 doubles read throughput and the > > slowdown of writes is negligable. > > Sorry, but I don't find that in actual benchmarks. Perhaps it is true > with some RAID controllers, but definitely not with the ICP-Vortex GDT > 6517. I get the same throughput from RAID1 on that setup that I get > from the bare Seagate Cheetah on that setup (no RAID).
It's perhaps worth mentioning that different hard disks can behave *very* differently. I have two controllers with a variety of matched pairs of RAID0 striped hard disks. All the disks give 6-7MB/s individually using hdparm. The IBM pair happily give ~11MB/s regardless of the RAID chunk size. The pair of Seagates *only* get the expected ~11MB/s when using a chunk size of 32k. Anything more or less and the performance collapses back to around ~7MB/s. It looks like (these) Seagates have "strange" caching strategies :-).
Moral: RAID is not a panacea. As with all IT you can't take anything on spec. Every "fact" has to be checked and double checked...
Mike
-- A train stops at a train station, a bus stops at a bus station. On my desk I have a work station... .----------------------------------------------------------------------. | Mike Jagdis | Internet: mailto:mike@roan.co.uk | | Roan Technology Ltd. | | | 54A Peach Street, Wokingham | Telephone: +44 118 989 0403 | | RG40 1XG, ENGLAND | Fax: +44 118 989 1195 | `----------------------------------------------------------------------'
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