Scalix on Dual Core or Quad Core?

[AaronM503]

All,

After the initial pilot test of scalix- my company wants me to get a new server and getting moving on putting into full production.

I've been doing some research and looking at prices and one thing I can't put my finger on is going with a Dual Core or Quad Core cpu server. Has anyone done any scalix (or for that matter, linux) benchmarks or reports using a Dual Core vs. Quad Core? More specifically I'm really interested in 2 - Dual Core vs. 2- Quad Core.

Any information on CPU performance / utilization would be appreciated.

- Aaron

[KevinAnderson]

Save your money on Processor, and spend it on Disk, and RAM, in that order.

Scalix will benefit most from fast disk. If the install is large, then mirror the drives where you're keeping the mail store, and keep them separate from everything else (OS, Swap, etc). RAM will be next in line. Scalix will benefit from additional RAM. This is especially true when you have a large number of SWA users. For RAM, you really need a 64 bit memory addressing to use more the 2 Gigs of RAM, so you'll want AMD64 or IA64.

In terms of the speed of the CPU, I don't believe you'll see any difference, anything vaguely current is plenty fast. Disk and RAM will be your bottlenecks. I'd bet money that a P4-1.7 ghz machine with Hardware RAID 1 and lots of cache on the controller, would blow the doors off a quad processor 64 bit Xeon 7100 3.4 ghz machine with software RAID 5.

Be aware that SATA drives are almost never the equal of SCSI. Not looking to start a fight here, but as a rule, SATA Drives are mated with lower end controller cards, or software mirroring. It's OK redundancy, but performance sucks, so the whole server is seen to suck. I don't mean to say that SATA CAN'T be the equal of SCSI, it can, but spend the money to on a good controller, with cache, and hardware RAID (mirroring preferred). Don't believe that a $50 controller card that says it supports RAID is the equal of a $500 RAID card, because it isn't. And fixing that later really sucks. I've fixed a few of them, as you may have guessed from the length of this post.

Kev.

[AaronM503]

Thank you for the response Kevin.

Yes, I will be investing in serial SCSI 10k rpm hard drives and 4GB of ram. I haven't decided yet on Raid 5 vs. Raid 50... most likely raid 5 (more of an established standard, I guess).. but if the performance improvement is really great; maybe I'll go with the 50 config.

Any thoughts?

- Aaron

[KevinAnderson]

Mirroring is faster than RAID 5. Raid 5 is not done for performance, nor does it provide performance. Scalix's recommendation is RAID 1+0.

How many users are we talking about here?

Kev.

[AaronM503]

450 Users, although I'd bet less than 75 concurrently.

-Aaron

[KevinAnderson]

What client are they using? Mostly Outlook? POP? IMAP? SWA?

Do think about something other than RAID 5. Or At least think about 1 controller card for the mailstore, and another for everything else. 450 is at the point where you will see issues with Disk if it's done really wrong. You can scale well past that if it's done right, but you'll see performance complaints if it isn't. I'd say that line is at about 100 users.

Kev.

[AaronM503]

95% will be web-based (fqdn:/webmail) except the handful of outlook connectors we have.

My boss is also interested in actually virtualizing the email server... (vm ware) I wonder what type of performance hit that will add.

Aaron

[obrodkin]

I've worked with Ricis' guys (Gregg is person to talk) and they have a complete manual on installing virtualized Scalix. Helped me a lot.

My setup:

Supermicro rackmounted server with 2x intel 5130 4Gb (soon to be 8GB) RAM
Zero channel RAID card to support internal HW RAID10 6x Seagate SATA ES drives (250GB)
LSI RAID SAS card to support external Promise J300 box with 12 SATA/SAS drivers

OS:
SUSE server 64bit hosts vmware (free version) with SUSE 32bit on top
Virtualized Scalix 3GB RAM
Virtualed OpenFiler 1GB RAM

I use LVM to manage available disk space both on host and guest OSs.