Hi-performance RAID/server question

flangeman

I'm building a high end machine for the build department where I work. I'm pretty much sold the idea that we should be pushing a 6 month turn around on each machines using high conumer parts rather than buying over sized, over priced Dell's withover long support contracts (that won't last the length of the machines use as a build server).

What I'm mainly looking for is a gain in HD write/read speed, there are some great deals on combo motherboards and Athlon64 4000 (only £220 down the computer fairs) plus DDR2 Samsung RAM at £120 for 510MB(all prices in sterling). Cheap stuff as you can see.

I've been looking at SATA Raid and after some research I think RAIDcore from Broadcom is the way to go. An 8channel card is available plus a 12 ch. Using RAID 5 or maybe nothing, can I utilize all channels with discs or does it have to be in sets of four? in other words can I stripe accross all 8 with no parity checking? or with a little.

Cheers in advance.

SwampThing

If you create a logical volume, RAID 0, at a hardware level, your OS will be presented with a single logical volume on which you create your drive; no redundancy at all - using all available disk space for storage. Loose one disk and all is lost.

Using RAID 5, you'll effectively loose one disk's worth of storage for parity. E.g. 8 X 100GB disks on RAID 5 will give you 700GB usable storage but you can afford to loose one disk without loosing the data.

Either way, your OS is presented with one logical volume on which to create your drive.

You're better off doing this at hardware level and not worry about striping at an OS level. That's what you're paying for the card to do. It's designed to do a job - RAID - so let it do it.

ressem

You can stripe across all, without parity checking. that's raid 0 though. Don't need sets of four
See raid 0 setup at.
http://www.tomshardware.com/storage/20040831/sata-raid-controller-20.html

Saruman

Are you saying you dont want parity?? On a server? Like SwampThing said you loose 1 disk and your in shít. Go with Raid 5, min 3 drives. Loose 1 (does not matter which) and the system still works fine off the 2.. replace the faulty disk and it rebuilds itself. No down time.

Capt'n Midnight

The old SCSI vs. IDE argument again..

Proper SCSI RAID cards don't rely on the processor to do data transfer and so a system with them is faster than an IDE system with the same data transfer rate.

Mirrored IDE drive (raid card) will have enough space and are a fraction of the price of a proper SCSI raid setup. IIRC you can read from either disk so can be slightly faster , but writes are slower. The other big advantage of SCSI RAID is hot swap and hot spare - if you can live without them then you have a lot of cash to spend elsewhere and you could use the machines as workstations after 6 months.

If you don't have enough ram use a different drives (or mirrors) OS / Swap file / Data so you don't have to wait for the head to move back for the next operation

Kali

Saruman wrote:

Are you saying you dont want parity?? On a server? Like SwampThing said you loose 1 disk and your in shít. Go with Raid 5, min 3 drives. Loose 1 (does not matter which) and the system still works fine off the 2.. replace the faulty disk and it rebuilds itself. No down time.

There'll still be down-time if a disk goes unless they're hot-swappable... but if theres a 6-month turnaround on parts I guess down-time isn't an issue, nor the problem of migrating to new hardware twice a year.. not something I as an admin would enjoy doing
Anyway for a generic build machine RAM and processor speed are your biggest issues... move older build versions to storage/archive boxes.

Capt'n Midnight

Kali wrote:

nor the problem of migrating to new hardware twice a year.. not something I as an admin would enjoy doing

Oddly enough it's not too bad doing that with windows 2000/2003, you do a full backup with NTBACKUP, do a clean install on the new machine and then a restore ! , there are a few tweaks in the reg because of the new HW and re-activation but not scary monsters.

flangeman

Saruman, parity isn't my highest problem, if I can save even an hour on the total build (as in compile time) I'll be made king of the castle. A failed disc every now and again won't kill me. The amount of zipping/unzipping and small header files that the current 'build' takes is humongus, massive amount of writing and reading.

Capt'n Midnight, I'm onto SATA at this stage not IDE, the new Seagate's (although I admit to being a Maxtor man, I have a lot of history there) spin at 10,000 and have some serious response times. Seems to have the SCSI guys running for cover (still more reliable I have to say). Anybody else have fun with a SATA array, RAID 5 or 0?

SwampThing, cheers, I got lost in my RAID definitions again!!

Migrating to new hardware, as Capt'n Midnight describes is nothing, plus it will ensure no little hacks get put on my machines by the dev boys.

Anybody else actually play with this stuff.

ressem

Just in case the order form is on the desk, there isn't DDR2 support with the AMD Athlons, apparently won't be till later till the dual core generation come out.

You're presumably looking at a PCI-X controller now, next generation will probably be a PCI- Express card. There's Opteron server motherboards that offer that, but don't know of any Athlon yet.
http://www.tyan.com/products/html/thunderk8we_spec.html

SwampThing

flangeman wrote:

Capt'n Midnight, I'm onto SATA at this stage not IDE, the new Seagate's (although I admit to being a Maxtor man, I have a lot of history there) spin at 10,000 and have some serious response times. Seems to have the SCSI guys running for cover (still more reliable I have to say). Anybody else have fun with a SATA array, RAID 5 or 0?

Well, in that case and money not being a factor, 8 X 72GB WD Raptor SATA drives in a RAID 0 setup is yer man - half terrabyte of lovliness!

http://www.komplett.ie/k/ki.asp?sku=122429&cks=PRL

That said, there are good performance reports from some of the 7200RPM 16MB cache NCQ SATA disks as well - NCQ is the key here.

Make sure you invest in a good RAID controller - it will make-or-break the setup and it's comparable in price to a couple of disks, which seem to be expendable anyway.

Any change you could expend a couple of Raptors this way, as a token of your unending appreciation for the sound, job-saving advice?