On Tue, 23 Jan 2007, Benjamin Smith wrote:
On Monday 22 January 2007 08:05, Matt wrote:
I am upgrading a very heavilly used email server to a AMD64 dual core
with CentOS. I am staying with i386 since the web GUI we use lists
64bit support as beta and I do not want any problems. The real draw
back I see is the max RAM on i386 but perhaps I am wrong. 90 percent
of our CPU load is Spamassassin. Disk I/O is likely a big bottle neck
as well. Currently we run 2 gigabyte of RAM but will likely move to
4G of DDR2 RAM. Moving from PATA to SATA drives as well.
SATA is better than PATA, but it pales compared to SCSI. Even with SATA, an
rsync of a large directory tree can hammer the performance of a server, but
with SCSI, it doesn't register enough, on a much busier server, to even
notice!
So, evaluate if the $500 for a *good* disk subsystem is actually worth it - in
my case, the answer is a resounding.... YES!!!!
I'm pretty sure this has nothing to do with PATA, SATA or SCSI.
Simply disks for SCSI are usually 10k or 15k versions with much smaller
capacities in multi-disk RAID setups instead of 4.2k 5.4k or 7.2k
PATA/SATA single disks with extreme capacities and smaller on-board
buffers.
Vide: my SCSI system has: 192 MB raid card + 6 x 15k 73 GB disks in RAID5
compare that with my PATA/SATA systems which are lucky if they have a 7.2k
disk with 8 MB cache.
Maciej
(not saying SATA is better, just saying the difference between the two is
very small, the difference is not from the protocol, it's from the
inherently more expensive and better hardware which is made for SCSI - as
a point of fact many of the cheaper PATA/SATA/SCSI drivers have the same
internals just different external connectors and possibly differing
firmware [different optimizations turned on - for server apps instead of
desktop single file streaming])
[plus servers have more RAM on the CPU for disk caching to begin with]
_______________________________________________
CentOS mailing list
CentOS@xxxxxxxxxx
http://lists.centos.org/mailman/listinfo/centos
