Input on RAID 1

Unless you are using an off motherboard RAID controller and SCSI disks don't expect much.

Scrut> I'm in the process of spec'ing a new system and am considering RAID 1 for

Raid 1 is slower overall than a HD by itself. It reads faster but since everything is written twice it averages out slower. I'm also in the process of spec'ing a new server, which I'll build myself, and Raid 0+1 is the way to go. No need to go SCSI. The newest 8mb cache IDE drives and Serial ATA (SATA) drives do very well. Take a look at

for some great tests and reviews. The problem with Raid 0+1 is that since it is "striped" (meaning everything gets read or written to the closest sector, for lack of a more detailed explanation) and mirrored (meaning everything gets written twice) it takes 4 HD's! To the uninitiated that's a lot of wasted money. But the payoff is speed and reliability. HD's are cheap. The formula is 50% "waste" for Raid 1 or 0+1, meaning half the drives get used for mirroring. By comparison Raid 0 is no "waste" meaning all the drives in the array get used for space.

Raid 0+1 is not as fast as Raid 0 but it's nearly as safe as Raid 1. The speed is somewhere in the middle. I think you'd be really impressed. For the best safety you could look into Raid 5 which uses 4 HD's in parity, meaning it's a big striped array similar to R0 but part of each drive "tells where the data is" so if you lose a drive you can rebuild and keep going.

I've found no motherboard that offers the kind of speed and flexibity that I want from R0+1 or R5 so I'm going with an external controller running at

66mhz. Most likely the Promise TX4000. You want a controller that offers as many connectors as you have drives, so if you're doing a R0+1 with 4 drives you want 4 connectors, setting each drive as it's own master.

I've given you enough information, or false information :) to get you started. Search the web for the rest and you'll end up fine.

- Eddy

We have a machine using RAID 0 which dramatically decreases the seek time of the drives. I know of someone that has RAID 1 on the mobo (not using for CAD)and it sucks. The RAID array has to periodically sync from master to slave so is no better than a separate backup disk. Go with RAID 0 off the mobo chipset with two 10,000rpm drives (eg. WD Raptor)and you wont be disappointed. Good luck.

Here's a quick tally of Raid speed/safety assuming equal drives, controller, etc....

Raid-1 2HD's: Safe but not necessarily fast (Called Mirroring, ~50% waste for comparison)

Raid-5 4HD's: Safe but faster than R1, slower than 0+1 (One of the most popular for servers, ~0% waste for comparison)

Raid-0+1 4HD's : Fast and safe, but not as fast as R0 (Called Striped and Mirrored, ~50% waste for comparison)

Raid-0 2HD's : Extremely fast but not safe; a drive dies you lose everything (Called Striping, ~0% waste for comparison)

Raid-0 4HD's - Even faster but not safe; a drive dies you lose everything (Called Striping, ~0% waste for comparison)

Raid-0 8HD's - Yipes fast! but not safe; a drive dies you lose everything (Called Striping, ~0% waste for comparison)

Incidentally I run R1 in my server now. I want faster speed with good margin of safety. That's why I am going R0+1 rather than R5.

- Eddy

RAID 0 will perform better, for now I'm just looking for data protection. For just a plain backup, does XP Pro have a backup feature that periodically copy selected directories to a backup disk at a set time? This might be a better solution than RAID 1 and lower cost than RAID 0+1 or 5.

Well Said Eddie!

My not so useful recommendation - stripe for speed + good daily backup system. Cache memory on card if possible. Mirroring useful, but not needed if a good system of backup exists. In my pastlife I had cached controller and fell in love - extra cache alone made life good and quited down the drive to a faint whisper - performance improvements too.

Regards,

SMA

we use a tape drive every night. we have 14 tapes so that we can go back 2 weeks if we need to recover anything.

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periodically

Is it stupid to think of a system with 2x 120 Go HD, 1/3 of it (2x40Go) on RAID0, the rest being used at night to backup the data on both drives? (just got one, with 8Mo cache, for home)

--> with no huge extra cost, RAID 0+1

My.01 Eu

JM

Windows built in backup, in a word, sucks. Look at "Backup MyPC" from

I use it - it is very good. Backs up to HD, CDRom, DVD, Tape, etc. It is the desktop version of Veritas Backup Exec.

- Eddy

periodically

Can you clarify? Are you using only 2 drives for psuedo RAID 0+1 by partitioning each drive for RAID 0 and then using a backup program on the remaining part of the drive ? How is this done and what are the drawbacks?

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Yes, raid 1 at night

Just a product of my imagination. I am wondering if it could be implemented, and how.