RAID Implementation Questions (3Ware 7500 Series)

[bschwarz6]

I’ve been thinking of implementing a RAID 5 array at home in my media server for a good amount of time, but I have never really had the need (read: had the money) to effectively implement one. I have read a bunch of reviews of HighPoint and Promise RAID cards, and have decided that neither of these brands will really put me where I would like to be, so I will most likely go with a 3Ware Escalade 7500 series (I have 5 200GB Seagate 7200.7 ATA drives).

Before I shell out the $409.99 for a 3Ware 7506-8 at NewEgg, I have a few questions (mainly logistical) about setting up the array, adding disks to the array, etc. I know that all RAID cards are different, so if you actually have this card (or its little brother, the 7506-4LP) I would really appreciate your help.

1- When creating the array, I assume that all of the disks should be blank (or you will lose your data). Is this correct?

2- How hard is it to add another disk to an array (eg: I have 5 drives now, how hard would it be to add a 6th?) once the array is created? Will I lose any of my data (or is there any risk?)?

3- Is it possible to add more than one disk at a time to an array? Will I lose any of my data (or is there any risk?)?

4- I run Windows 2000 Server. How will I go about making changes to the array? Is there a Windows-based UI or will I have to re-boot and enter the firmware UI during boot?

5- How long does it usually take to initialize an array the first time? What about when I add a disk to the array? Or replace a bad disk?

Most importantly … how happy are owners of this card overall? Is there anything that you wish 3Ware had done differently? I’ve seen a lot of benchmarks and it appears that 3Ware is the best for speed, but how does it perform in the real world?

Thanks for any and all of your help.


Brad

 

[DougLite]

1) I'd make sure there isn't any data you want to keep on the drives, that's for sure.
2} Expanding a RAID-5 array on the fly is exceedingly difficult, if not impossible.
3) See number answer to #2. If more than one disk in the array fails without a rebuild, all of the data's gone. and I don't think you can dynamically expand the array, although it allows for hot spares to automatically rebuild if a member of the array goes down.
4) 3Ware has a web-based management program for Windows and Linux - Check it out at http://www.3ware.com/products/pdf/3DMDS4-30final.qk.pdf
5) A Hardware XOR engine will speed things up significantly, assuming that 3ware installed a half way capable unit. However, 5 200GB PATA drives are going to take a while to cook on creating a RAID-5 array on any controller. I have no idea exactly how long, but you could probably grab a latte at Starbucks in the meantime.

My additional comments/questions/concerns: Do you have a backup strategy? Even with RAID-5, a virus, your own error, or a catastrophic system failure (power supply blow-up etc) can still trash your data. I post this a few times a week, but RAID is no replacement for a backup scheme. Looks like either tape or lots of dual layer DVDs for you. Also, look at uninteruptible power protection and a high quality and high output (particularly on +12V) PSU for this system. Additionaly, do you have a plan to deal with an event that causes the controller/array to be unavailable or if the controller does fail? Do you have a system with PCI-X slots, or at the bare minimum 66MHz PCI? Also, don't look for a worthwhile increase in throughput unless you're moving huge files in and out all the time.

 

[bschwarz6]

Thanks for all the input DougLite...

The card would go into a dual P3-733 system with 4 gigs of RAM. It’s got a few 64-bit PCI slots and I was looking forward to taking advantage of the 64-bit slots with something other than gigabit Ethernet.

That web interface for the card looks pretty cool ... I hadn't seen that before (for some reason).

I do have a UPS protecting power input for the server and this is by no means my only backup method (its not really a backup method at all). I have a 5-tape DLT carousel backing up on occasion (usually once a month) and a DVD burner that I plan on taking advantage of in the near future. I also back up all of my important data nightly to an off-site server.

I am not really worried about the card going bad, as I could easily restore critical data to my workstation rather than the server, and this is not a business application, so although downtime sucks, it wouldn’t cost me money. Realistically I could go a few days without most of the data.




As far as expanding the array is concerned, I was under the impression that it varied in difficulty and reliability from card to card. Do you run this card? Expanding my array was a major point in creating the array at this point for me because I didn’t want to shell out for drives AND a controller. I figured I could get the controller now and get the drives later.

Is expanding a RAID 5 array impossibility with ALL cards? or just this one?


Thanks,
b

 

[ambit]

I have 3 of those cards at work, and 4 of the 7506-4's at work/home, so I can kinda help
1. Any data on the drives will be destroyed when you create the array.
2. With the 7500-series you cannot expand an existing array. You can create a second array with the new drives, but to make the initial array larger you need to delete it and recreate it with the new drives.
3. See above - You can add multiple hot spares to an array/s though.
4. You can do simple management through "3DM", all major changes (like destroying the array, making a new one need to be done through the BIOS) You can add hotspares and initialize/rebuild the array from Windows.
5. One of the servers has 6 x 120Gb 7200rpm drives in RAID5, it took a long time to initalize the array the first time. It currently holds about 200Gb of data and takes ~3hrs to rebuild the array if a drive dies.
Another has 7 x 300Gb 5400rpm drives in RAID5. That thing took forever to init/format, pretty much kicked it off Friday, checked on Saturday and finished on Sunday. It rebuilds ~1.2Tb in about 8Hrs.
These servers boot from 10K SCSI, the IDE is only for mass storage. The first one has been in commision about 3 yrs now, the second one about 1.5yrs. No hardware failure or loss of the arrays, yet..

I really like mine and consider it one of the best choices for PATA hardware RAID.

 

[DougLite]

*Applause* Good job implementing a solid storage system across the board. I think you're ready to go, and you should invest in that pretty darn good 3Ware controller to finish the project. Good luck, but with all of that fault tolerance, you won't need it!

 

[bschwarz6]

Thanks for all your help so far ... for some reason I thought that RAID5 arrays were more dynamic than that ... I guess not ...

I run Windows now, but if I were to choose to run Linux (or upgrade my Windows box) would it be possible to move the drives and RAID controller to another box (or OS) while keeping the array (and its data) in tact? How risky is that?

Thanks,
Brad

 

[DougLite]

You'll need to read up on using NTFS volumes on Linux. You will not have to destroy the RAID array, but you may be forced to reformat it (which is every bit as bad for the data o nthe array). I do not recommend FAT32 on a 1TB array - the cluster size would be way too large and FAT32 was simply not designed for partitions this big. You could partition the drive partly in NTFS, partly in FAT32, and partly in a native Linux journalised FS, but that kind of defeats the purpose of having one big array. Windows would work with the NTFS, Linux can work with a Linux FS, and they both should be able to read/write FAT32.

 

[ambit]

I've moved [array & card] from one Win2k3 machine to another. Once you feed the new machine the drivers it finds the array/partition/drive. I've also moved one from a 2k machine to a 2k3. This was all NTFS though, i've never moved between Win & Linux.
I know the array information is on the drives & controller. You *shouldn't* loose anything as long as both OS's can see the file system.
As DougLite said, Fat32 would be the most "compatable" But i'd never use it on an array this big.

 

[Farva]

i was thinking of making a raid 5 array myself. this is good information. i sure wish i had more money to create the array once and not have to recreate it every time i would add a drive. the array being talked about here is pata, not sata? im looking into both alternatives because of price. i know toms hardware talked about making a software raid 5 array in windows xp. either way i need more money.

 

[uzor]

So, assuming the main concern is a hardware based array which will net 1 large volume, what would you guys recommend as a solution that would allow dynamic expansion of the array? Or does such a beast not really exist?

 

[ambit]

the array being talked about here is pata, not sata?

Correct. The 7500 Series is PATA only.

So, assuming the main concern is a hardware based array which will net 1 large volume, what would you guys recommend as a solution that would allow dynamic expansion of the array? Or does such a beast not really exist?

SCSI
I know some of the new SATA RAID adapters, 3Ware 9500's, LSI, etc can expand the array, but i don't know about the partition. You would need Partition Tragic or something for that.

 

[bschwarz6]

i was thinking of making a raid 5 array myself. this is good information. i sure wish i had more money to create the array once and not have to recreate it every time i would add a drive. the array being talked about here is pata, not sata? im looking into both alternatives because of price. i know toms hardware talked about making a software raid 5 array in windows xp. either way i need more money.

this was exactly my problem. I already have 3 identical 2200GB PATA drives, placed an order for 2 more and dont have the cash to up it to a total of 8 with the RAID card ... i wasn't at all looking forward to backing up 1TB of data (tapes to accomodate that would be expensive) to make the array a little larger, so i think i will wait ... save some money in a jar ... and finish the array all at once.

I was sort of kicking myself last night for not going SCSI from the start, but it was almost a year ago when i started this project, and SCSI was way out of my price range.

Thanks again for all the useful information. Keep it coming!


b