It's the same money if you factor in the 3ware controller. Even without a caching controller, SCSI works good in multi-threaded IO (not withstanding crappy shit from Dell or Compaq). You can get such cards from LSI for $75. And of course, many server MBs come with LSI controllers built-in. Our older 32-bit production servers all use Linux software RAID w/ SCSI and there's no issues when multiple users/processes hit the DB.

*Maybe* a 3ware controller w/ onboard cache + battery backup might do much better for multi-threaded IO than just plain-jane SATA. Unfortunately, I have not been able to find anything online that can confirm or deny this. Hence, the choice is spend $$$ on the 3ware controller and hope it meets your needs -- or spend $$$ on SCSI drives and be sure.

Now if you want to run such tests, we'd all be delighted with to see the results so we have another option for building servers.

Alex Turner wrote:
It's hardly the same money, the drives are twice as much.

It's all about the controller baby with any kind of dive.  A bad SCSI
controller will give sucky performance too, believe me.  We had a
Compaq Smart Array 5304, and it's performance was _very_ sub par.

If someone has a simple benchmark test database to run, I would be
happy to run it on our hardware here.

Alex Turner

On Apr 6, 2005 3:30 AM, William Yu <[EMAIL PROTECTED]> wrote:

Alex Turner wrote:

I'm no drive expert, but it seems to me that our write performance is
excellent.  I think what most are concerned about is OLTP where you
are doing heavy write _and_ heavy read performance at the same time.

Our system is mostly read during the day, but we do a full system
update everynight that is all writes, and it's very fast compared to
the smaller SCSI system we moved off of.  Nearly a 6x spead
improvement, as fast as 900 rows/sec with a 48 byte record, one row
per transaction.

I've started with SATA in a multi-read/multi-write environment. While it ran pretty good with 1 thread writing, the addition of a 2nd thread (whether reading or writing) would cause exponential slowdowns.

I suffered through this for a week and then switched to SCSI. Single
threaded performance was pretty similar but with the advanced command
queueing SCSI has, I was able to do multiple reads/writes simultaneously
with only a small performance hit for each thread.

Perhaps having a SATA caching raid controller might help this situation.
I don't know. It's pretty hard justifying buying a $$$ 3ware controller
just to test it when you could spend the same money on SCSI and have a
guarantee it'll work good under multi-IO scenarios.

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