Stefan Cars wrote:
Hi!

Following up on this I'm also looking into buying some servers and have
the almost the same scenario, a MySQL DB together with apache with
mod_perl and embperl, (alot of SQL and dynamic content). Would we be
better off with:

Dual Xeon, 2.4 GHZ with 2GB of RAM or Xeon 3.0 GHZ with 2GB of RAM
and
RAID-1 on three disks or RAID-5 on three disks.


Will the difference between 2.4 and 3.0 really do that much ? Isn't the SMP system better.

Kind Regards,
Stefan Cars

With that small a difference in CPU speed for the purpose you state, I'd definitely go with the dual 2.4 Xeon setup. Unless the FreeHSD SMP implemetation is _really_ bad, which I haven't seen any indication of at all, the SMP system will perform better when you're going to have multiple relatively heavy duty processes and threads running at once, as in the case of a web server with dynamic content hitting a database.


Someone commented on RAID-5 with 3 disks being useless- it isn't, but most setups have at least a hot spare designated, and some vendors (IBM, unsure of others offhand) also 'extend' RAID-5 to include the hot spare in different methods (ie RAID-5E, RAID-5EE).

Some relatively experienced comments on your config-
Add more disk if possible. A striped (2x disk) OS dedicated disk will improve performance a bit, but you'd probably do better using seperate physical disks (or logical RAID volumes but comprised of different physical disks) between the database and the web content, resulting in less I/O contention between the two (web server and DB).


RAID-1 across 3 disks is a bit of overkill IMHO, as you're still limited to a bit less than the throughput for a single disk. Use a single disk (or striped pair) for the OS (seperate disk for swap if you anticipate heavy swapping), a RAID-1 mirror for the Database data/files, and another disk for web content. If the content is reasonably unchanging, (the HTML), or you have the content in a source control or content management system, then the DB data is arguably more important so should get the RAID redundancy...then just back up the HTML and web content regularly, or perhaps snapshot it to spare space on the RAID volume nightly. That woould be something along the lines of:
Vol 1 (non-RAID or RAID-0 striped of $ allows, so single or dual disks)- FreeBSD


Vol 2 - web content. Single disk or RAID-1 mirror, again depending on $

Vol 3 - DB content. RAID-1 mirror, only for DB use.

If heavy swapping is expected, then allocate swap space on one of the other disks, but it will obviously affect performance.

Do NOT use a single RAID-5 for both web and DB, unless performance is secondary- you _will_ see high amounts of I/O wait states as the server becomes more loaded. If $ allowed, making each RAID-5 or RAID-1 but using seperate physical disks for each volume would be ideal..some RAID hardware and/or software allow you to span different types of RAID configurations across the same disks, which is great for the budget (ie 3 physical disks, but having a RAID-1 volume across _parts_ of two physical disks, and the rest being a RAID-5 volume), but again, you'll eventually run into disk seek and I/O issues...

Scott



On Tue, 2 Mar 2004, Scott W wrote:


Joseph Koenig wrote:


I'm putting together a system that will host a relatively small database
(around 20,000 records), as well as run Apache / PHP to search that
database. I have the option in front of me to use a P III dual 1GHz machine
with a SCSI Raid 5, or to use a single P4 2.8 GHz with a SCSI Raid 1. Both
have 1GB RAM. I'm looking to use MySQL as the DB. The site that this machine
will host gets about 2 million hits per months (yes, hits, not pageviews or
visitors) from about 21,000 unique visitors. Does anyone have an opinion as
to which machine will perform best under this scenario? Obviously, both
would run FreeBSD. Thanks,

Joe Koenig
Production Manager
jWeb New Media Design
[EMAIL PROTECTED]
http://www.jwebmedia.com/
636.928.3162

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Someone else already mentioned this, but RAID-1 will be faster than the RAID-5 at the storage level, if the RAID-5 array is a relatively small # of drives. If you're talking about 2 disk RAID-1 versus 10 disks RAID-5, those numbers may change. If the drives are integrated into the systems, it's also possible the RAID-1 disks are faster drives than the RAID-5 drives...

If you're going to run the DB and web server on the same system with a
high percentage of static pages, the SMP system may help out.

If you have almost all dynamic content is full of complex DB queries,
the P4 would do better based solely on CPU speed.

How about RAID-1 on the dual PIII and keep the P4 as a workstation? :-)

The PIII is likely up to the task, but it really depends on the type of
content (is _everything_ PHP generating dynamic content, every page
hitting the DB etc?)

Scott

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--
Stefan Cars
Snowfall Communications
Tel: +46 (0)18 430 80 50 - Direct: +46 (0)18 430 80 51
Mobile: +46 (0)708 44 36 00 - Fax: +46 (0)708 44 36 04



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