RAID Questions ...

[twvette]

Just learning as I am considering this setup for a new computer soon to be ordered or built ... did a search and found good info but still these questions:

1. Is RAID 0 really worth it performance wise ??? I assume its overkill for basic applications but does it really help for video transfer/editting ... my current computer chokes/crashes big time and behaves differently depending upon which one of my drives I save to ... so, this is the main reason I am upgrading. My current PC doesnt have SATA and drives are also a bit slow. So, if I go SATA 7200RPM 8MB cache do I really see a significant boost if I then go RAID 0 setup or is it barely noticeable ???

2. Was originally interested in RAID for data "backup". Now that I understand RAID a bit a RAID 0+1 seems very tempting. The PC I am thinking of ordering looks like I can only go Raid 0 or 1 from vendor so I would have to add two more same size drives for + setup. How is this done in XP to go from Raid 0 or 1 to the + setup ??? Do drives have to be formatted or just a setting cahnge ???

3. In Raid 0 files partially exist on the two drives right ??? Its also my understanding they show up in Windows explorer as two drives of the same size. So, say I want to copy a file to say an external USB drive for whatever reason .... how is this done ... in other words, how do I select half on one drive and half on the other to make it a complete file ??? I must have missed something here ...

4. In Raid 1, say one of my drives goes bad. How do I know one has gone bad and that I need to replace it ??? I assume there is a message of some type but just curious. Once replaced does Raid automatically rebuild the replaced drive on its own or is there a process to go through to get it become a mirrored copy again ??? Just rying to figure out how seemless Raid really is ...

5. There seems to be some disclaimers that Raid is for integrity ... not backup. Ok, I understand that people dont want to call it a backup because its still at some risk if it resides in same system (shock could kill both, etc.). Thats fine for businesses to justify for integrity only but for consumers is it reliable enough to most of us to rely on it as backup ??? I mean do you trust it as the only backup source for all yuor digital photos and videos of your kids or are you still nervous enough with it to very frequently be backing up to CD, DVD, Tape, etc ??? Of coarse I would still do say monthly or quarterly backups to external hard media as you never know but if you feel you have to backup each time you transfer a large group of pictures or new video, that means you dont trust Raid much. I guess my point is, its alot of money to spend for consumers if it truely cant be trusted as a primary backup with periodic backups to external media.

Bare with me ... and any help further understanding/clarifying is appreciated ... thanks in advance

[glc]

1. I personally don't feel RAID 0 is worth it, it's more of a fad right now. It will give you higher benchmarks, and many people will tell you they can notice a difference. If performance is of the utmost, I'd get either WD Raptor 10000 rpm SATA drives or Seagate SATA II "NCQ" 7200 rpm drives (with a motherboard that supports NCQ). The best combination is a Raptor for your OS and applications, and a NCQ for your big files.

2. RAID 0+1 is a good system. It requires 4 drives and (very important) a compatible controller. This gives you the speed of striped RAID 0 and the data integrity of mirrored RAID 1.

3. No, you have it backwards. A RAID 0 shows up as just one drive. RAID 0 stripes data across 2 physical drives and shows up as just one volume. RAID 1 is a pair of drives with identical data on each.

4. I can't answer that as I've never used a straight RAID 1. I would assume it's dependent on the capabilities of the controller and its firmware and utilities.

5. Call me old school - the only RAID that I trust is RAID 5, which until recently was only SCSI. It's now available on high end SATA controllers. It's an excellent system, but requires at least 3 drives and even more to work right. The minimum reliable array is 4 drives. The way it works is it stripes 2 or more drives and has one parity drive. Therefore a 4 drive array has the capacity of 3 drives. This gives you the performance of striping with integrity. If any one drive fails, it can be swapped and rebuilt with no data loss. RAID 5 controllers also support hotspares and on the fly rebuilding - and even hot swapping. I recently built a couple storage servers this way - I used an Adaptec 8 port SATA RAID controller card and 8 Western Digital 250gb RAID optimized SATA drives. I built a 6 drive array with 2 hotspares. Array capacity is 1.16TB (a 250gb drive is actually 232gb). The controller ain't cheap - it's 500 bucks. Regardless of this integrity, I still don't trust any RAID as the ONLY backup solution. My customers with RAID 5 servers still have a tape drive. For consumers, it all depends how important your data is to determine a backup strategy. External to hard media is fine, but if you create any really important files in between backups, it would be wise to protect them in some fashion.

Bottom line - RAID striping can improve performance at the higher risk of data loss (one drive croaks, you just lost everything), RAID mirroring is strictly for data integrity (one drive croaks, you are still in business), RAID 5 is the best of both worlds at a high cost, but no RAID is the total answer to any performance or integrity issues.

RAID 1 - what happens if your system gets attacked by a virus or you make a big boo boo and delete some stuff you didn't mean to? The RAID doesn't help you. Both drives will be affected, only external backups will save your bacon here. Same applies to RAID 5 or RAID 0+1.

RAID of any type is of questionable value for consumers. The money would be better spent on external or removable backup equipment. Just my opinion.

[bozo]

I too, was very excited when I built a system 2 1\2 years ago using RAID mirrored. Worked flawlessly until last summer...when I got a warning that one of the drives was bad. I bought a new drive, and expected to experence a smooth change over as it was suppost to do...WRONG

Mysteriously, before I installed the new drive, the RAID configuration changed to "Stripped"...through NO action of mine. Now I was "hosed", with NO chance of rebuilding the supposed bad drive.

After months of troubleshooting, I eventually formatted the new drive, & reloaded everything to the single drive (this was an easy changeover since my RAID drives were still functional & I could configure them as a slave to move my data.

A search of my username for a thread called "Broken RAID" will give more details of what I went through. In the words of glc "Raid is not ready for prime time" when it comes to single PC users. No more RAID for me!

Oh & BTW...neither of the RAID drives were faulty as I have formatted them both, & now use them as slaves.