Are there any RAID experts in the house?

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Mrs Peel
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Are there any RAID experts in the house?

Post by Mrs Peel » Tue Mar 21, 2006 2:22 am

I have just been given a RocketRAID 454 card by a friend who installed it just once and decided it was too difficult to set up. So basically it is brand new and surely it's got to be better than my crappy promise onboard RAID I am using at the moment.

Link here: http://www.highpoint-tech.com/USA/rr454.htm

I've never used RAID 5 before and so I am in need of some experienced tech advice of what would be the best way to set this thing up here in order to get the very best speed performance and also keep my data secure at the same time.

I currently have here 3 x ST3160023A Seagate 160gb Ultra HDD's with 8mb cache and unfortunately cannot afford to buy any more drives at this time.

So I am interested in how the experts who have had personal experience with RAID 5 would suggest I could make the very best use of these three drives that I have.

Thanks for reading in.

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Ghostrider
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Re: Are there any RAID experts in the house?

Post by Ghostrider » Tue Mar 21, 2006 9:37 am

Mrs Peel wrote:I have just been given a RocketRAID 454 card by a friend who installed it just once and decided it was too difficult to set up. So basically it is brand new and surely it's got to be better than my crappy promise onboard RAID I am using at the moment.

<snipped>

I currently have here 3 x ST3160023A Seagate 160gb Ultra HDD's with 8mb cache and unfortunately cannot afford to buy any more drives at this time.

So I am interested in how the experts who have had personal experience with RAID 5 would suggest I could make the very best use of these three drives that I have.

Thanks for reading in.
I presume 1 of those drives is your "C" drive, if so then leave it that way, you will need to purchase a new 160 then make a raid 5 using the remaining 3 drives, or as Raid tends to screw up at some point and recovering data from a screwed raid is a pain, i would recommend using "C"for OS, "D" for Data and "E" for clone image backups of "C" & "D" and get a good price for the raid card.... :wink:

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Post by RogueSpear » Tue Mar 21, 2006 3:32 pm

I hate to say it, because I know it's not the answer you're looking for, but I would agree with Ghostrider. I'd stick with mirrored pairs if you're going to bother at all with the card. The only time RAID 5 makes any sense at all is when you're running a high demand server that can actually benefit from the speed gain AND the drives are hot swap capable. Otherwise I just stick to plain old boring mirroring.

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Post by Judge_MC1 » Tue Mar 21, 2006 9:39 pm

Hi Mrs Peel, nice to see another Kiwi :)

Thing to remember with IDE RAID cards is most of the cheaper ones (i.e. under NZ$800) are still doing software RAID - your CPU does all the RAID calculations. IDE RAID is a little bit of a have as you'll never see great leaps in performance using it - its more for data security or if your really dont care about your data, to make a great big JBOD array. SCSI RAID is a totally different story tho.

You probably already know this but wikipedia has a great page on RAID

http://en.wikipedia.org/wiki/Redundant_ ... AID_levels

You need a minimum of 3 disks to do RAID5 and you will always loose part of the overall RAID Array capacity to the parity information.

With all that said for a home file server that your accessing over a network IDE RAID5 rocks, you can be confident that your data is safe, have a huge partition for your files - bigger is always better so they say ;)

BTW Windows 2K and up are capable of doing software RAID without a RAID adapter, which I actually prefer because you can expand the array on the fly. I have seen a hack to allow non server versions to do RAID5 too.

Hope that helps.

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Post by Mrs Peel » Tue Mar 21, 2006 10:12 pm

Hey there! Also nice to see another kiwi on here ;)

I do a heck of a lot of high end graphics and video rendering here on this box so really I am trying to squeeze out as much extra speed as I can possibly get. I keep all my data ghosted back onto regular IDE drives for backup so really I just need these puppies as a fast array for OS (running win2003 server hacked as a workstation) and rendering.

If I was to use these three seagates here together on a RAID5 array how much "actual" drive space would this give me in total - there's the part that I am struggling to get my head around with this RAID5 dealio.

:?

PS: One day when I am filthy rich I will upgrade my dual PIII mobo to a nice dual Xeon one with onboard SCSI RAID, but I don't see that happening in the next 24 months LOL :P

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Post by Judge_MC1 » Tue Mar 21, 2006 11:21 pm

With RAID 5 you loose one disk to the parity information.

/me hugs his Quad Xeon 700Mhz Dell PowerEdge 6400 RAID 5 SCSI array :)

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Post by Mrs Peel » Wed Mar 22, 2006 9:13 am

OK then, so my 3 x 160gb seagates will give me 320Gb storage on RAID5. Cool bananas, that's more than enough drive space for my needs.

Any idea how much improvement in speed performance I would get with these three drives on a RAID5 compared to 2 drives on a RAID0 setup?

And also, is a RAID5 setup likely to shorten the lifespan of my hard drives cos there is more read/write activity?

/me spanks Judge_MC1 for being such a skite :P

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Post by Judge_MC1 » Wed Mar 22, 2006 5:11 pm

Umm, not 100% sure but I would think that the RAID0 would be faster overall but keep the following in mind.

RAID0 (Striping) would give roughly the same performance as a single disk - possibly seeing burst transfers roughly twice the top speed of a single disk. Most people would use RAID0 for a scratch disk (recommended for graphic design/video editing).

RAID1 (Mirroring) would give faster read performance but slower write performance as it has to write the data to both disks. Most people would use RAID1 for an OS disk.

RAID5 (Striping w parity) would give roughly the same performance as RAID0.

Now the caveat here is that it’s IDE, which is limited in the amount of commands that can travel the bus at the same time, and your controller is still handing off all the RAID calculations to your CPU, hence RAID5 may actually be slower than a single disk depending on your CPU, Bus, cache, etc.

You can also tweak block/stripe sizes (on some controllers) to configure the array for the type of work it will be doing i.e. smaller size for better sequential reads and larger for better random reads. Cant say I have ever done that tho.

One other factor that affects the overall array speed is caching – a lot of people recommend disabling the onboard cache on the drive if using it for RAID and using dedicated cache on your RAID controller. A friend of mine uses a 512MB RAMdrive as his RAID cache using smart disk caching software but he has two SATA 10000RPM Raptors in RAID1 on an onboard SATA RAID controller.

If speed is a big concern I would recommend getting a couple of WD Raptor X RAID edition drives - not cheap tho, so you make do with what you’ve got…. ;)

Any RAID setup is likely to stress the drives more than “normal” usage, but in practice I haven’t ever found that drives in a RAID array die faster than drives that aren’t. You still awake after all that waffling?

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Post by Mrs Peel » Thu Mar 23, 2006 8:50 am

Yeh still awake - well as awake as can be expected at this hour of the morning hehehe - it was a good waffle to read and I understood you more clearly than the techno-babble I read about RAID on many websites.

I just finished a 3 year stint as a student and I am penniless at the moment so an expensive computer upgrade won't be on the cards for a long time yet - most likely Raptors will be obsolete technology by then LOL

I had another question but ermmmmmm my brain is fried today and I forgot what it was DUH :?

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Post by Judge_MC1 » Thu Mar 23, 2006 7:02 pm

Yup, I know I would love a couple of Raptor's in my main box, but the bank manager (my partner) would seriously sell all my gear on Trademe if I splurge too much.

I've done the student thing.... so I know exactly what its like until you get back on your feet - student loans are a killer. I make do with what I have or can get cheap. Good luck with the RAID setup, can sometimes be a bit frustrating when your new to it. Yell out if you need anything :)

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Post by Roguedog » Thu Mar 23, 2006 11:32 pm

Q.
Any idea how much improvement in speed performance I would get with these three drives on a RAID5 compared to 2 drives on a RAID0 setup?

A.
2 drives at Raid 0 would always give the best performance vs 3 drives at Raid 5 due to the overhead of calculating parity data on Raid 5.

I looked up the raid card and I believe the fastest would be four HDs as Raid 0 which would definitly be hardware raid.

Due to to the limitation of the IDE spec, eg. master and slave on same channel can't read or write at same time, trying to add a 5th or 6th HD, in a Raid 0 or Raid 5 even if supported would be a combination of hardware and software Raid which would add more overhead.

I have also been doing my own video editing and have been using a Raid 0 (stripping only) with two IBM 80gigs for data and a 30gig for boot.

The performance boost for udma100 is 33MB sustained on the boot drive and 70MB sustained with Raid 0.

Q.
And also, is a RAID5 setup likely to shorten the lifespan of my hard drives cos there is more read/write activity?

A.
A good Disk Defragger will extend the life of any harddrive Raid or not. I use Raxco Perfect Disk http://www.raxco.com/products/perfectdisk2k/ wrks great. Running a defragger every couple of days is the best protection for your harddrives. Knock on wood, I haven't had a drive go bad in several years.

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Post by Mrs Peel » Fri Mar 24, 2006 1:00 am

ROFLMAO @ Judge_MC1 I'll keep an eye out on TradeMe for you then ;)

Thanks for your reply Roguedog, so from considering all your collective opinions here it looks like I better fork out for a fourth drive and aim for a pair of striped array.

And here is the question I forgot to ask last night when I was having my blonde moment....

Is it worth me bothering with this PCI IDE Rocket Raid card at all then? Do y'all think I will get a better performance with this than using my current promise onboard RAID? I am not fond of onboard IDE RAID really, but that's just a subjective opinion rather than a fact-based one.

Final opinions please?

Cheers

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Post by Ghostrider » Fri Mar 24, 2006 9:47 am

Mrs Peel wrote:ROFLMAO @ Judge_MC1 I'll keep an eye out on TradeMe for you then ;)

Thanks for your reply Roguedog, so from considering all your collective opinions here it looks like I better fork out for a fourth drive and aim for a pair of striped array.

And here is the question I forgot to ask last night when I was having my blonde moment....

Is it worth me bothering with this PCI IDE Rocket Raid card at all then? Do y'all think I will get a better performance with this than using my current promise onboard RAID? I am not fond of onboard IDE RAID really, but that's just a subjective opinion rather than a fact-based one.

Final opinions please?

Cheers
I really don't like the OS drive being part of a Raid so my setup would consist of 160gb OS drive and the other 2 160gb drives Striped as Raid0 for performance, just be aware that if 1 of those drives dies then you lose your data...!!!

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Post by Roguedog » Fri Mar 24, 2006 5:36 pm

I agree with Ghostrider in that I don't want my OS as part of a RAID setup.

I have the onboard Promise IDE RAID and Love it, though it is limited to just 2 drives in a stripped array. I set the Swapfile and temp dir to the array drive.

My Suggestion would be to use your current drive or go get a 40 or 80gig/133UDMA Hard drive for OS and then RAID 0 the 3 160gigs.

I am presuming you have a DVD burner. So after setting up the OS and the RAID I would Ghost the OS drive to the array than burn the ghost image to a DVD.

For the your DATA on the stripped array I want to pass on this;

There's two types of computer users;

those that have lost data,
and
those that are about to!

If you back up your projects regularly theres no need for RAID 5.

Hope this helps.

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Post by Judge_MC1 » Fri Mar 24, 2006 7:41 pm

Well I guess my take would be any sort of IDE RAID array is kind of pointless in terms of performance... the whole idea of RAID is redundancy.

If you want fast access, seek and read/write times, get SATA 10K RPM drives. That said you can stroke a bit more performance out of your drives in a striped array, so yes that would be a good way to go (remembering you loose the redundancy).

I always setup any server I build with a mirrored OS array, but they're usually SCSI drives. I dont run RAID on workstations cause its a pain in the ass :P

One thing to consider is putting the drives on different controllers, using a combination of the onboard controller for your OS disk and the HPT controller for your RAID array, which will at least (hopefully) minimise bus contention issues.

Have you considered using JBOD (just a bunch of disks) if your controller supports it. Its fairly easy to recover from since the data is written to the first disk, once its full it writes to the next disk, etc - and generally provides pretty decent performance. Just a thought.

And yes I think the HPT controller would be a better controller than the onboard promise as generally onboard raid controllers are limited versions of the add-in controllers you can buy.

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Post by Mrs Peel » Sat Mar 25, 2006 1:02 am

Thanks again for all the suggestions.

As far as the OS drive goes, I consider my OS partition basically disposable for the following reasons: This is my work PC and I run a very very minimal install here just absolute essentials. After I setup a new windoze install I ghost that image and restore it back regularly to keep my OS nice and fresh and zippy. And since working with nLite and addons I am regularly updating my OS ISO which I can have reinstalled in an hour when needed. I never ever use my OS drive for data storage and I never will.

Being a graphic designer and student as well I have learned to be fastidious about data backups so I have a spare IDE drive which I keep offline except to hook up weekly to do a full backup of data drives and I also have an external fireware drive that I keep on hand for incremental backups which I might do several times a day if I am working on a serious job.

I've lost four drives over the last 18 months - two of them were RAID drives - but it was only as inconvenient as the time it took to shove a new hard drive in my box and restore my backups. I regard RAID drives as pretty much disposable also.

Anyways, my system is getting old here and I upgraded pretty much every piece of hardware I have but always looking for an opportunity to squeeze better performance out of my hard disks cos IMO that is the bottle neck of my overall system speed. But we can only work with what we have available.

The Highpoint RAID card hasn't cost me anything, but it's the best I can financially afford to work with at the moment until I have a few thousand dollars cash spare to totally rebuild my system with a new mobo/CPU/RAM/SCSI setup.

Alrightee then, better get back to work on finishing the addons I need to toss into my upcoming ISO build.

Cheers for all the input guys. Muchly appreciated ;)

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Post by ron2024 » Sat Mar 25, 2006 4:57 am

For what it's worth I'll put my 2 cents in. Staying with a "good" onboard Raid Controller
is your best bet, any "PCI" card type Raid Controller will be limited by the Bus Speed
that your Mother Board runs at. Now I understand that you don't want to spend any money
right now. But when you are do your homework, for I know there definite differences for
OnBoard Raid Controllers concerning the speed capabilities. I currently have 3 of the 4
Onboard Raid Controllers that I'll talking about, the Intel Matrix is the fastest one.
Hard drives, WDRaptors/10,000rpms/Striped on all 3 Raid Controllers & the "OS" on all 3.
I've never had any problems & of course you make your "Regular Backups" of your "OS"
just incase.

Now for the speed ratings;
Intel Matrix: 124,000 to 125,000 KB/s
Via Technologies,Inc.: 110,000 to 112,000 KB/s
Promise Technology,Inc: 78,000 to 80,000 KB/s 2 different Mobos, same slowest speed.
Silcon Image: I can't recommend them, I tried out 2 different Mobos, neither one worked,
returned both.

The above speeds are with WD/Raptors/10,000rpms/Striped, with 72,000 rpm drives, you'll
have lower/slower speeds, Mirrored you'll have lower/slower speeds, on all types.

IDE "Regular"type Hard Drives: aprox. 34,000 to 55,000 KB/s.
Truth is Onboard Promise sucks, it's slow.
The "WD Raptors" on a Promise Contoller is just a waste of money, for there not that
much faster than a good IDE hard drive, 55,000 vs 78,000 (80,000 max, w/OS only).

Oh & WD Rators have the market share, so far no one else has put out 10,000rpm drives
for same/similar price. I'm not talking just about speed bursts here these drives kick
ass, everything runs faster.

Bottom line, I don't think that Raid Controller someone gave you will do you any good,
for the current Bus Speed that your Mother Board runs at will kill any speed increase.

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