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Home -> Community -> Usenet -> c.d.o.server -> Re: EMC -or- SSA?
On Sat, 08 Nov 1997 16:15:12 -0600, "Ken L. McDermed" <kenmcd_at_dmm.com> wrote:
>My company is in a war right now over using SSA or EMC disk storage. My
>thought is to go with SSA because of the speed of the serial channels,
>being able to see physical drives, etc, etc. All cost aside, does anyone
>have experience on both drives w/ Oracle?
>
>
>Thanks - Ken
I have a cleint where we looked at this.
We concluded that EMC was grate for Oracle provided you have enough cache. We run 2 TB of data with a total of 8 GB of cache. The speed of access if phenomnenal. It is especially good at data loading in to the warehouse, where writes happen by writing to the cache on the EMC array.
One trick you need to be aware of is that EMC is still SCSI, ie it is an arbitrated bus. So you can only have one read or write happening on the bus at a time. Normally, this is not a problem, since the array caches as much as possible in to memory automatically. Hence, most of the time, you get very near to 20 MB/s transfer rates.
I have never seen a single stop or unplanned outage on the Oracle databases caused by the disk lose. Disk problems ar detected in advance, flagged to EMC via the call home link, and the first we ever know that there is a potential problem is when the engineer calls up to say he wants to replace a drive. Beleive me, a lot of people sleep a lot more comfortably knowing this works.
On the other hand, SSA, especially the new SSA, is a good system. It not open, its an IBM solution (we use our EMC systems on many different vendors hardware). However, SSA is better if you will doing small, random read/writes. Hence I expect SSA to perform better in a file server environment. This is because the SSA transfer speed is a lot higher (theoretically its closer to 80 MB/s, but I have seen that achieved in a non-test environment), and its not arbitrated.
Bottom line - EMC is very good on Oracle.
Call me if you want more details.
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