Okay....Raid 0 or Mirrored Drives?

Ronald Epstein · 10-02-2006, 06:58 AM

I have the opportunity to possibly make some changes to my
computer configuration.

Originally, I set up two (2) 74GB 10,000 RPM Raptor Drives in
a Raid 0 Stripe configuration.

The idea was to have those two drives working together as
one 148 GB drive. This configuration was also designed to
increase overall speed.

I do understand the risks. If one drive fails, so does the other.
In fact, that has already happened within the first year of use
Fortunately, the computer is under warranty. the drive was
replaced, and everything was backed up to an external drive
so no data ever got lost.

But now I am looking to possibly consider a change.....

I don't know what it is called, but some have suggested it may
be better taking the two (2) separate raptor drives and setting
them up as mirrored drives where all the information on ONE drive
is automatically mirrored on the other.

The downside, I suppose, is that I'll lose 74GB. of available
storage on the second drive. No big deal as I have another
drive with 200GB of storage.

So, what would be the overall advantage of changing from
a Raid 0 setup to a mirrored setup? Would you recommend this
over my current Raid 0 setup? Finally, in order to make this
change is it just an issue of making a simple change in the BIOS?

Thanks in advance!

Al.Anderson · 10-02-2006, 08:27 AM

The two options RAID you describe are used for differeent purposes.
.
RAID-0 is generally used for speed (or throughput if you want to be picky). If you are running an application that wants to write to the disk rapidly (say graphics/movie generation) you would probably make use of RAID-0. Even playing high end games would benfit from RAID-0 as they get data off the disk quickly.
.
RAID-1 is used for data safety. If one of your disk fails, you are not impacted as all of the data is on the other disk. Thisis usually used for data server systems. (And behind the scenes the 2nd disk is replaced during system maintenance.)
.
If you are doing backups I can't see needing a dedicated RAID-1 on a home system. If you are flush with cash, there are RAID options which combined both RAID-0&1 for the best of both worlds; but then you have to get a high end RAID controller to handled the data traffic or you lose the spped advantage.
.
To make the change you alter setting on your RAID card. (Not the computer BIOS.)

Tekara · 10-02-2006, 10:01 AM

Considering that harddrives are mechanical with comparitively shorter lifespans than the remainder of your hardware, setting drives up in RAID 0 is always considered risky for important data. However though, RAID1 is no substitute for backups, it will only keep your hardware alive. If there is a corruption in your data, it will be propagated through the system.

RAID0 is fine if the data on your computer isn't that important or if you keep good frequent backups handy. Pretty much if you can recover from a bad disk in a couple hours without any stress then there's not much to worry about.

Since it seems like your interested in what others are doing, I personally use a RAID5 with four disks in my home server. RAID5 is generally considered to be a compromise between performance and being able to use as much of your disk space as possible.

Kimmo Jaskari · 10-02-2006, 11:44 AM

Quote:

Originally Posted by Tekara

RAID1 is no substitute for backups, it will only keep your hardware alive. If there is a corruption in your data, it will be propagated through the system.

There is protection against that too, as well as accidental deletions, but you'd have to run Solaris 10 and use ZFS - you get checksums on everything from start to finish and you can run snapshots automatically on a regular basis to guard against accidental deletions.

Of course that doesn't help a lot in this case... I agree though that it's a question of what one prioritizes. RAID1 is usually a more sensible approach than RAID0 though, assuming you don't need the maximum possible speed.

Chris · 10-02-2006, 01:12 PM

Well, RAID-5 is more then just "add another drive" he'd have to have a controller, onboard or PCI, that would manage it. RAID-5 is something that works out slick for most cases, as you gain some nice features - you get 2/3 of the space vs. half, and your performance is fairly good read/write.

RAID-0 is fastest, read and write, no data safety.

RAID-1 is just as fast as RAID-0 on READ in most cases, but slower on WRITE. Data safety in that both drives are mirrors, so if one drive fails, you're OK.

RAID-5 is not as fast at read as either RAID-0 or RAID-1, but it's faster on write then RAID-1, and you don't lose as much space. RAID stays alive and kicking able to rebuild. Here's the hitch for Ron: he'd have to buy another drive, have a PSU that would support hanging another raptor, and he'd have to have controller level support for RAID-5; true on some MOBOs, not all, and the controller cards that do RAID-5 aren't nearly as cheap to get a decent one.

Up to you Ron, what is the end goal?

**HTF Ads**

Al.Anderson · 10-02-2006, 03:23 PM

I can't see using RAID5 for a home computer.

I should add that I set up my PC by using a non-RAID drive-C, and a D drive using RAID0. The C-drive has obviously has the OS, plus normal data files (Word, Excel). I have my games and home movies on my D-drive; which I back up (mostly) frequently.

Tekara · 10-02-2006, 03:32 PM

raid5 is generally seen in home use, most commonly due to it being a great compromise between performance and lost space for redundancy. Aside from that parity calculation is expensive which results in it not being seen much in commercial server environments, raid10 is preferenced here for it's stronger performance and better fault tolerance.

I do like your setup though Al, make sure you set your page file on your RAID0 to further boost your performance!

Christ Reynolds · 10-02-2006, 10:52 PM

Quote:

Up to you Ron, what is the end goal?

yeah, we need to know this before any questions are answered. raid-0 isn't actually raid at all, since the R in raid stands for redundancy, and raid-0 has none. aid-0 is more accurate, but almost never used.

raid-0 and raid-1 are totally opposite ends of the spectrum, so you need to tell us what your plans are. (minor increases in) speed, or decreased risk of data loss?

CJ

Al.Anderson · 10-03-2006, 07:49 AM

Interesting info Robert, thanks! I guess I have to review my RAID material. I don't remember what I did with the paging file; so I'll check into that this weekend. (I love tweaking for performance - even when I don't need any more!)