2 HD RAID1 Setup & Partition Question

[ChrisBud]

Hi Gang:

Am setting up a new Athalon 2.60 DAW and trying a RAID 0 array for faster performance; I have the option when reinstalling to determine HD partitions (ie: likely 64MB) or none at all; (in either case I understand the RAID0 treats both HD as one HD, writing data to both HD at increased speed); Any recommendations if Partitons (or none) will work better in a RAID0 configuration ? (I'm aware there's no redundancy here on backing up-will do it manually).
Have read both the Tascam and ProRec WinXP configuration guides; Not alot covering RAID use; Appreciate any experienced info; Thanks.

 

[Hawking]

Determining the partition depends on a couple of things.

1. Do you have another drive (besides the 2 in the RAID array) that you will be using for your operating system?

2. Are the 2 drives in your RAID array the same size?

3. Are you looking for the best audio performance, or will the computer be used for womething else as well (video, internet, etc...)


If the drives are not the same size, and you partition one of them into say 2 partitions, you will usually lose that same amount of space on the other drive.

Partitioning is useful if you have a large disk that you want to put an operating system on. For example, my computer has, among others, an 80 gig drive that's partitioned into a 15 gig and a 65 gig partition. The 15 gig section holds my operating system, and the 65 holds my archived data (audio, video, yadda, yadda).

Best audio performance will come wit using RAID 1 as long as your operating system doesnt have anything to do with your RAID setup.

The ideal scenario is something like the following...

10-40 gig for operating system (formatted NTFS if your using a compatible operating system)

4 drives of whatever size (80 gigs are about $80 now) for audio.

The 4 drives are run at RAID 10. RAID 10 is a combination of RAID 1 and RAID 0. Raid 1 is striping and gives you about twice the speed (the machine is writing different data to 2 places at the same time). RAID 0 is mirroring, wich is just another name for duplication. If you duplicate your RAID 1 array, you get the speed advantage of RAID 1 and the redundancy of RAID 0. If 1 drive fails, you simply replace it with a new one and rebuild the array. Any drive of the 4 can get screwed up without losing anything.

As long as you are installing your OS to a seperate drive, RAID 1 will give you better performance than no RAID at all. If you are using 2 80 gig drives, you wind up with 160 gig of storage. As far as partitions go, I don't think it's necessary in most cases, since you should be using a seperate drive for the OS anyway. The advantage of a partition is to divide one disks' boot records and other critical disk information onto 2 seperate entities. The computer sees them as 2 seperate drives. Useful for security, or to save data if the OS partition needs to be reformatted (you can reformat 1 partition of a drive without touching the data on the other partition).

Have I babbled enough? I'll let someone else babble for a while...

 

[ChrisBud]

I've got only 2 80G HD's configured to RAID-0 for best performance, using NTFS; Since I don't yet have 2 additional HD's to go to a RAID-10 (I understand what you're suggesting on both mirroring to prevent data loss + 2HD in RAID0 for best performance) configuration;

With only the 2 HD in RAID0, Would you suggest at this point either:

1) 1 Big HD via RAID0 w/no partitions
for O/S and Audio.....OR

2) Partitoning the RAID0 for O/S XP system and programs (say 30G) and the rest of the HD partitoned for audio only..
OR

3) If I picked up a 3rd HD for strictly the O/S, could it be any HD (ie: not matching in GBsize or rpm, since the other 2 would be config'd at RAID0 for audio only...
Thanks; Appreciate the insights.

 

[Hawking]

I strongly recommend getting another drive. It can be any size, although a 30 gig would be more than sufficient. You need to keep the operating system away from your audio files. If you don't you'll be negating the advantages of the RAID array. The idea is to be able to write audio to one place and let the CPU access the operating system from another place at the same time. In your case, the third drive will not be part of the RIAD. It functions as a stand alone drive on a standard IDE channel (usually on the motherboard).

Again, I don't think a partition is necessary for the 2 80 gig drives in the RAID. If you get a third drive that's over say 30 or 40 gig for your operating system, you can partition say 15 or 20 gig for OS and leave the rest for something else. As I said before, the partition is really just for isolating problems as a crash or error on one partition won't effect another partition. Harware failures are a different story though. If the drive itself fails, obviously, you'll lose all of the partitions on that drive.

 

[ChrisBud]

Thanks for the recommendations; It seems the more I research the various threads on RAID options, the more confusing it gets (see below); Perhaps it might be easiest to get the 3rd HD for the O/S & 2 HD's in the RAID 0 config (is this called a RAID headache?....); Thanks.


OldGrover
Senior Member

Registered: Jul 2000
Location: Ontario, Canada
Posts: 239

You can't do RAID with only one disk. Here's the rundown :

RAID 0 - This isn't "real" RAID since it is not Redundant, but most people count it. This is the striping option mentioned above - it increases speed, but, if anything, decreases liability (because you lose all the data if one drive goes, not just the contents of that drive)

RAID 1 - mirroring. Two drives, each in sync with each other. With a good controller, can increase read speed. With excellent controllers, no noticeable speed decrease, but because they have to keep in sync, some degradation is possible.

RAID 2 - "Hamming Code ECC" striping. Similar to RAID 0, but with fancier algorithms and ECC (Error correcting) disks - this means that if one drive goes down, the data is still intact within the RAID set. Rarely used in practice because it is inefficient in terms of disk space required. Rarely supported on RAID controllers. Very fast.

RAID 3 - Parallel transfer with parity - similar to RAID 2, but more efficient use of disks. Very fast. Quite commonly supported. Minimum 3 disk setup.

RAID 4 - Independent data disks with shared parity disks. Minimum 3 disk setup. Very very fast read rate. Slow write rate. Very commonly supported.

RAID 5 - Independent Data disks with distributed parity blocks. Fastest read rate. Fairly quick write rate. This is the most common RAID level for corporate systems - although 0+1 is becoming more common as disks drop in price

RAID 6 - a version of RAID 5 with more redundancy (you can lose more drives before losing data). more expensive, less efficient use of disks, very rare.

RAID 0 + 1 - basically two stripe sets mirrored together. Takes at least 4 disks, but has excellent performance characteristics combined with some redundancy (can lose any one disk)


Now, most homerecorders are more worried about speed - especially write speed. RAID 0 is probably reasonable, provided downtime is acceptable and provided a backup solution is in place. For pro studios, I would recommend a 0+1 solution - relatively cheap and very fast. Hotswap drives at that point would be a very good investment, along with a controller that supports them.

Example - at work I've got a fileserver - an IBM Netfinity 5500 with 5 x 10000RPM 36gb SCSI hotswappable drives arrange in a RAID 5 configuration . Now, that means that if any drive goes down - any drive - the system keeps on running, keeps on serving files - it just sends a message to me and I walk into the machine room, see a little red light on one of the drives. I yank the drive, put in a replacement and, within a few hours, the drive is fully integrated into the RAID and life goes on. During all this time, the server never stops serving files, never has to pause, we are just in a vulnerable state since we are not redundant. Two hours later, we're back redundant and the users never noticed. A RAID 0+1 system would work similarly.

RAID 0 vs 0+1 is a question of balancing money vs redundancy. If you do this for a living, go for 0+1 - the first time a harddrive dies with a client in the studio, you'll have made your money back in not having to reschedule. If it is just you, well - how much is your time worth to you? How much is that perfect riff you just nailed on the harddrive worth? Your call.

Now, since I am a professional paranoid, I'll just mention that RAID is no substitute for backups. It doesn't matter how redundant they are, if your studio catches fire, they'll still melt.

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