Raid 5 questions

[caleb1019]

Hi, I've been looking all over the internet and I couldn't find answers to these questions, so I'm hoping someone here might have a little experience with this.
Ok, here goes. I currently have two IDE harddrives, same exact drives. Both of them are just about full though, I have them running normally not in any raid array. I was thinking about getting 3 or 4 more of these same exact drives and putting all 5 or 6 of them into a raid 5 array.
Now I figured I can either buy a nice cheap IDE controller and do a software raid with win2k or xp.. or 2k3 eventually.. (these harddrives will all be on a spare computer which does nothing more then act as a file server, for only 3 people). Or the other option is buying a hardware raid controller with at least 6 channels, 4 is too little. As far as I can tell if I want something like that it is gonna cost me at least $200, probably a little more. Although if you know of any cheaper please let me know =)
Anyway, I still haven't gotten to the real question, that was just some background info.
So, since I need to eventually add the data from the first two drives to the array, is it possible to build an array from drives that already contain data without losing the data? There is too much stuff on them to copy it somewhere else temporarily also. (about 250gb) If that wouldnt work, could I build an array out of the three blank drives (assuming I had 5 drives, 3 blank and the two with data) and then copy the data over, delete the stuff from the two original drives, then add them? Or is it not possible to add drives to an array at all after it is built?
Last question, I have read a little about a program called Veritas Volume Manager, I think that was the name, and the impression I got was that it interacted with the built in raid functionality of windows and gave you some extra software raid options (maybe such as adding more drives?).
Well that is about all, If you took the time to read this then thank you very much =)

Also, keep in mind the main purpose of this array is just that I need a very large storage space that has some kind of backup, so raid5 seems to be the best solution, and software might be the way to go cause of it being much cheaper. Speed isn't too much of an issue, since probably it will only be accessed by 1 or 2 people at once, through the network.

 

[Robor]

As far as I know you can't expand a RAID array once it's been created. One option would be to get the new drives, setup your RAID5 array, and copy the data from your existing drives to the array. Then take your old drives and sell them. I recently did this. I had a single WD120 and created a RAID5 array with 3 WD120. I sold the old WD120 to my friend. Oh, I'm using a 4 channel Promise SX4000.

If you have any questions please PM me 'cause I don't venture out of Distributed Computing often.

 

[techfuzz]

After you create a RAID array there is no way to expand it by adding more disks by just plugging them in. RAID arrays, especially RAID 5 and above require parity bits that are spread across the drives in a KNOWN pattern. The pattern is determined when the array is created and cannot be broken unless you break the array and wipe the disks.

Veritas Volume Manager is a cross-platform RAID and SAN management application to look at the status of your disk systems.

Recommend Solution:
Western Digital 80GB SE (WD800JB) - $110 each x5 = $550
Promise SuperTrak SX6000 - $250

Assuming the computer you going to put all these drives into has enough space, you could go with 5 or 6 of the 80GB drives and that IDE controller for less than $1k and have room for your 250GB of data with some space to spare. If you plan on adding any data, definitely consider using 120GB or larger drives. They're currently $140 each these days and you could get away with as few as 3 or 4 and still have bunches of space to grow. If you wanna go all out then get some of the 200GB drives that are running around $250 each. 6 of those and you'll have 1 TB of usuable space after making the RAID array.

techfuzz

 

[caleb1019]

Oh man, no way to put these drives in an array then unless I can find 250gb of space to use temporarily I guess. Thanks for clearing that up though. So how about using just a normal IDE controller and software raid5 from windows? I won't be booting from this array, and the operating system will be on raid1, so it should be safe. You both talked about using hardware raid, I was looking at the sx6000 and it looks nice, but do you really think it will be much better.. (as in $250 better?)

One more thing, this little discussion I found seems to say (I think) something about veritas volume manager being able to add disks to an array?
Any other thoughts? Thanks again.

link to other discussion ([url]www.experts-exchange.com)[/url]

 

[nemo160]

as far as i know raid 5 is only supported by hardware controllers, as calculating the parity bit would eat a bunch of cpu cycles
read through the AT ide raid guide, its a bit dated now, but the majority of the info should still be applicable

 

[chizow]

I would check out this round-up from Tech-Report, as its the most recent and well put together RAID review I've come across. One caveat, which I e-mailed the author about, is the poor 3ware write scores. I'm not sure if he set-up his array as a dynamic disk, as I was experiencing poor performance until I upgraded (on advice from 3ware tech support).

You shouldn't have any problem copying the data from the 2 drives to the new array; just use something like Ghost or Drive Image and it should work fine. The only thing I would be concerned about is having 2 PCI RAID controllers with bootable BIOS' in the same rig. I've read of problems with that in the past. As for being able to add 2 more drives to an existing RAID 5 array, I'm not sure this is possible. However, it might work, as 3ware's RAID 5 will rebuild itself on the fly (and the array is still fully functional) in the event of drive failure based on the parity bits on the other drives. This is probably a question best asked of 3ware. There is a webform that you can ask questions, and they are amazingly responsive. I had my ? regarding write performance answered the next day.....very impressive.

The question of the hardware involved is pricy though. For a RAID 5 array with 5 disks, you'll need something like the 3ware 7500-8, which goes for $418!!!! If you really wanted RAID 5, I'd nix a disk and go with the 4-channel version at a much more palatable $285 or so. These prices are Newegg quotes, and may have gone up in recent days. You can see Newegg's 3ware offerings here. I purchased the 7000-2 about a month ago and it was only $126, now its $149!! You can probalby find them cheaper on pricegrabber as well. Keep in mind, that the Tech-Report findings on the 3ware 7500 are probably off, I saw a 300-1000% increase in performance (ATTO, Diskbench, Diskspeed32, IOMeter, Sandra) after I upgraded to dynamic disks through WinXP.

Chiz

 

[IanthePez]

I was under the impression that raid 5 is one of the only ones that actually allows you to add drives to it...

 

[ProviaFan]

Originally posted by: techfuzz
Promise SuperTrak SX6000 - $250

Does that include the cost of the ECC SDR SDRAM that's needed for the controller? If not, add $40 or so for a module. That controller does appear to be more affordable than an equivalent 3ware RAID 5 IDE controller; I wonder how they compare in performance.

Edit: Nevermind. Just saw Chiz's link, and am reading it now. Thanks.

 

[caleb1019]

I found a pretty good review of the 3ware 7500 at www.pimprig.com.
Also, from that review it sounds like you can add drives to the array.
"You can also initialize RAID rebuilds and add drives to the array from the interface which is navigated via a web browser and can even be accessed over the net should you decide to enable this feature."
Can someone who has a 3ware 7500 comment on this? =)
That card looks pretty nice, and as far as support I think 3ware from what I've heard is a bit better than promise.

 

[Pariah]

Now I figured I can either buy a nice cheap IDE controller and do a software raid with win2k or xp..

WinXP does not support software RAID 5. Only Win2k Server or higher support RAID 5. Shelling out $700+ for software that supports RAID5 for the purpose of RAID5 would be rather retarded when you can find better performing and more robust ATA hardware controllers for less.

As far as I can tell if I want something like that it is gonna cost me at least $200, probably a little more.

I wouldn't recommend any ATA RAID 5 cards except 3Ware, and the 8 channel is $365 at Hypermicro.

So, since I need to eventually add the data from the first two drives to the array, is it possible to build an array from drives that already contain data without losing the data?

No.

If that wouldnt work, could I build an array out of the three blank drives (assuming I had 5 drives, 3 blank and the two with data) and then copy the data over, delete the stuff from the two original drives, then add them?

Many SCSI RAID controllers support online array expansion, but I'm not aware of any ATA RAID cards that do. I scoured 3Ware's website for confirmation on pimpware's claim but couldn't find any data for or against it. You would think a feature like that would be listed, but no where could I find where it specifically said it didn't either.

Last question, I have read a little about a program called Veritas Volume Manager, I think that was the name, and the impression I got was that it interacted with the built in raid functionality of windows and gave you some extra software raid options (maybe such as adding more drives?).

Again, I wouldn't recommend Win2k RAID5. There are better cheaper options available.

You can see Newegg's 3ware offerings here.

Hypermicro sells 3Ware products for less and shipping is free if you mention StorageReview.

 

[caleb1019]

Well, I emailed 3ware to ask them, since everyone has different opinions about adding drives. I'll let you guys know what they say. That 8 channel raid card is looking pretty good if I can add drives. Wow this will be my 6th post since oct 2001, and the 4th in this thread, lol.