Raid 0 Hard Disk... fast but... ??

will-3 wrote on 6/9/2008, 7:10 AM
I just bought a SimpleTech Duo Pro Drive.

Two 500 GB Hard Disk in a single case.

Looks like I can set it to be Raid 0 or Raid 1.

Raid 1 is slow because everything you save to the first disk automatically gets saved to the second disk.

Raid 0 is fast because divides your file into small sections and writes to both disk... this means part of the file is on one disk and part is on the other... this is fast because Hard Disk are slow compaired to the computer... so while the first Hard Disk is busy seeking and writing... the computer puts the next part of the file on Disk 2.

At least that is the way I understand it.

The possible issue... if you use Raid 0... you now have two disk drives with half your data on one and the other half on the other... these are mechanical devices... so if either fails... your data is gone... unless of course you buy a second Tera Byte drive and backup to that periodically.

What has been you guys experience with such drives?

Thanks for any comments.


Comments

richard-courtney wrote on 6/9/2008, 7:44 AM
There are other Raid types. Mostly depends on your controller.
I use Raid 5 that has speed and redundancy. Your files are saved in parts
on each drive so if one drive fails (degrades) you can rebuild it when you
replace the bad drive.
Chienworks wrote on 6/9/2008, 12:13 PM
"so if either fails... your data is gone"

That argument is specious. How is that different or worse than having only one drive with no RAID at all? If you have only one drive and it fails, your data is gone then too.

RAID 5 is probably best if you can afford it because then you do have both speed and redundancy.
Jeff9329 wrote on 6/9/2008, 12:56 PM
Will:

Running RAID 0 on an external drive is not really a good idea in my thinking. You are right that Raid 0 doubles your chance of data loss since you are depending on two HDs for storage. And if you don't optimize your stripe size, you may not get any performance increase.

A good hardware based raid controller will let you run RAID 0+1 so you get the benefits of both performance & redundancy. You will need 4 drives to run this.

An external drive array (except NAS) should be for longer term data storage, sharing and backup. They can pretty easily be fast enough for a working drive if it is high quality. I have found the raid controllers can vary in speed and quality pretty significantly.

For all RAID scenarios you still have to consider stripe size carefully. Especially when optimizing for video files.

I believe the current mult-HD external drives on the market are kinda a mixed bag if you are at the 1TB or lower size because you may as well have a 1 TB data only drive inside your machine.

When you are getting up there in size like a 4 to 16 TB array, you almost have to go external and you can set up an awesome optimized RAID array.

RAID 1 should not present a significant slowdown with a good controller. Just stick with it for now.

Im really on a ramble at this point.


bsuratt wrote on 6/9/2008, 1:04 PM
RAID 5 requires at least three drives but IMHO is probably the best arrangement for RAID array. Fast and relatively safe. I have three 750GB drives in a RAID 5 array which nets 1.36TB of storage. If you lose one drive simply replace it and it will rebuild using data from the other two drives. If you lose two or more drives at the same time you are up the creek. Yes, I still back up important data from the RAID to an external drive! Works fine for HD editing.
LReavis wrote on 6/10/2008, 2:42 PM
I use a pair of Raid 0 750 GB drives as my main work drives. I used to use Raid 5, but worried that a power supply malfunction could blow up the 3 drives and I'd be left with no way to reconstitute the array. So now I have a pair of external drives that get their power from another source. They are not set up as Raid drives (it's generally not possible to set up a USB Raid array), but instead I use one 750GB drive mounted as a folder inside of the other 750GB drive. That way, I can use synchronizing software (I use Sychronize It, but I believe there are free downloads now that also work well) several times per day to read my work drive and then copy new or modified files over to the external drives, with little worry that power supply failure in my computer will blow up all my drives.