SATA or SCSI drives? 7200 RPM, 10K, or 15K

[Steve Cousins]

I'm in the process of ordering a server to run ColdFusion and MySQL with Linux.
I was planning on using SATA 7200 RPM drives but one option is to go with SCSI
and get either 10,000 RPM or 15,000 RPM drives. Of course the price goes up
quite a bit with the faster drives so I was wondering if there would be a
noticable performance boost by going with the 10K or 15K drives?

Or, are there people using SATA drives with sizeable ColdFusion sites that
find that the performance is fine? Would I be better off getting more memory
(I have it configured with 4 GB of RAM right now) or faster CPU's? I'll be
getting a Dual CPU machine with Dual-core processors for a total of four cores.
I was planning on getting the 2.0 GHz Opterons but perhaps faster CPU's would
be better than faster disks?

Any help is greatly appreciated.

Thanks,

Steve

[ke4pym]

Any current generation of SCSI is going to be faster than SATA. SAS or serial
attached SCSI is going to be even faster. For production environments, SCSI
will provide better performance.

While this next bit doesn't quite equate to what you're doing, it will provide
some prospective.

I used LoadRunner to test one of our applications on a high end server running
off of SCSI. LoadRunner would log in, perform a task and log out. On SCSI,
that task took an average of around 12 seconds. I then switched the CFML code
base over to a SAN connected disk. The same LoadRunner test completed in an
average of around 3 seconds.

Buy as much server as you can with your dollar. CF in a stand alone install
can only use a max of around 1.5GB of memory (current JVM limitations and
32bit-ed-ness and all). If you go multi-server and cluster instances together,
you'll get extra performance from that.

Working on the server day-to-day, you'll likely not notice that extra 5k of
RPM. But as load ramps up and you start looking at your metrics, that extra 5k
of RPM will eventually become apparent.

[Steve Cousins]

Thanks for the information. I'm not sure about what you say about "Any current
SCSI drive being faster than SATA" (what if both drives are 7200 RPM?). In
any case, it is interesting to see the performance difference you showed with
SCSI vs. SAN. That is quite a difference. I'm guessing the difference is
single disk vs. RAID to get that kind of performance boost.

You bring up an interesting point about memory and 32-bit-ed-ness. Any idea
why ColdFusion hasn't gone 64-bit? Any idea when it will? I'd think the
ability to have lots of memory for caching purposes would be a big performance
boost.

Thanks again for the reply.

[ke4pym]

My initial test was done on a system with RAID 5 and the RAID controller had
320MB of on-board RAM for cache.

By any current SCSI disc, I meant recent discs and technologies. Namely, SCSI
Ultra320. I can't say as I've ever seen a 7200 RPM SCSI disk. I know SATA has
caught up with some of the internal things that make SCSI faster, but it still
isn't quite there yet.

I don't know why CF hasn't gone 64 bit yet. I'm sure it eventually will.