Another Software RAID question 2

[rburke]

Well I'm dreaming up some File Server specs for work but have ran into a problem. I want to have a multi-TB RAID array using RAID 5. At first I was looking at hardware-based RAID solutions, but after your discussion on Software RAID, I've decided to do that. It is just a dedicated File Server box so the CPU utilization isn't much to worry about on Dual Opteron 242's.

Anyways the question I have is the array is going to consist of 10x WD RAID Edition 250 GB SATA drives plus 1 spare drive. Then there will be a seperate array for the OS and will consist of 3x Raptor 74GB drives. Both arrays will be software RAID 5. So I need 14 SATA ports, I was looking for 2x 8 channel SATA controller cards but they don't seem to exist. There are plenty of 4 channel ones, but anything above that is a RAID card, either hardware or software. My questions is does any one know of any 8 channel PCI-X SATA controller cards? If not, does anyone know of any RAID cards that it would be able to by-pass the RAID fearures and just use as a 8 channel SATA card?

I appreciate the help on this.

Ryan

 

[thedaver]

I think you'll potentially be very disappointed in a software RAID 5 on that scale. The CPU utilization is going to be rather high and may introduce artificial latency. Be very deliberate in your analysis.

http://www.surfinbox.com/hosting/

 

[ericbrunson]

thedaver's right. You would really be a lot happier looking at a hardware raid solution. I've heard good things about the promise cards, but I've never used one.

 

[clonny2]

It really depends on the hardware being used. It is true in most cases hardware raid is faster that software raid. But I know of cases where that the software raid is faster.

>---------------------------------------Lawrence Feldman
SR. QA. Engineer SNAP Appliance
lfeldman@snapappliance.com

 

[rburke]

clonny2:

Can you expand on some of those "cases" when software is faster?

Everyone:
I appreciate your comments and concerns. My only problem with hardware have been driver problems in the past. I have only used Promise cards, but they have very poor Linux support by only releasing binaries for certain "buggy" kernels. Does anyone have any other suggestions about good hardware based SATA RAID cards with good Linux driver support? I'll probably go with Suse 9.1 or 9.2, possibly Fedora Core 2 for the 64-bit OS. Could that lead to problems if I try to run the 64-bit OS? Does anyone have any real use benchmarks of software RAID 5 from personal experience (I've Googled alot of links, but just looking for more info, like always.).

Thanks again for the comments.

 

[marsd]

Good Luck.
Excellent feedback on your problem here:

http://ask.slashdot.org/article.pl?sid=04/10/30/184256&tid=198&tid=4&tid=106

BTW:
The promise raid controllers are pretty bad from all accounts and my own experience with them, utilizing an additional ide
controller that advertised higher throughput than the onboard,
was truly terrible. This was 2000 so YMMV.

 

[thedaver]

I haven't followed their product line as closely as you might prefer, but the 3Ware SATA controllers are very much linux friendly and have all sorts of models as far as scaling to your solution.

I would encourage you to do some careful research. Clonny2 may be making an accurate statement that some cases may exist where software RAID5 is "faster". But that doesn't address the circumstances of the load, the nature of the application relative to your's, the configuration of the RAID hardware. Nor does "faster" necessarily mean stable, easy to build, or easy to administer.

There are a lot of fast Ferrari's in the shop for repairs that can only be repaired by skilled Ferrari mechanics....

http://www.surfinbox.com/hosting/

 

[rburke]

This is really only going to be a file server with SMB, FTP, and of course SSH, also possbily NFS. The box is mainly going ot be used for backups, but possibly host some network mounted file systems through NFS.. that hasn't been set in stone yet. So I'm not too worried about the applications, but I just wanted to get some experiences from the Tek-Tips gurus on if the system proposed in my inital post should be able to handle the load of software RAID 5 with that amount of disks. It will probably have 4 GB RAM and dual Gigabit Ethernet NICs.

I appreciate all the comments so far and keep thme coming if anyone has any other ideas.

Ryan

 

[chiph]

I was also going to suggest 3Ware.

Their site lists that their 9000 series is supported under:
Microsoft Windows Server 2003 (x86, Opteron)
Microsoft Windows XP (x86, Opteron)
Microsoft Windows 2000 (x86)
Red Hat Linux 9.0 (x86, Athlon)
Red Hat Enterprise Linux 3 WS (x86, Athlon, Opteron)
SuSE Linux 8.2 (x86, Athlon)
SuSE Linux 9.0 (x86, Athlon)
FreeBSD 4.9 and 5.2 (x86)

Chip H.


____________________________________________________________________
If you want to get the best response to a question, please read FAQ222-2244 first

 

[LawnBoy]

If it's not hardware based, it's not RAID, IMHO.