Is RAID 0 really that unsafe??

[crt1530]

<< However using a 250MB drive and a 17GB drive in the array will be more trouble than it is worth. >>



Congratulations, TRUMPHENT! You just won the &quot;Didn't read the posts correctly&quot; award. Stand by for your smack upside the head!

 

[MortimRex]

OK ..let me throw this question into the mix. I have a RAID 0 setup with two 30GB drives. I went out an bought Ghost 2001 to help curb the possibility of losing by data. I open the book and it states that Ghost will not work with Raid 0 arrays.

So, is there a program that will work with striped arrays?

REX

 

[Diffusion]

<< RAID0 = Lie

RAID = Redundant which RAID0 is not.

I personally feel that large hard drives are so cheap not there is little sense in using RAID0. Sure it looks great in benchmarks and to trump your neighbors. Why flirt with disaster?

Windogg >>


Your thinking IDE. 180gb (.18tb?) Seagate SCSI drives are over 1500$ last I checked, they make even bigger disks (cray made some that were in the .5 terabyte and larger range not that long ago, I think they are even bigger now), but they are even more expensive. Large disks are pricey, but if you need that kind of space, you should not even be examining IDE, much less PC hardware in general. I helped spec out some stuff for a bioinformatics group, they wanted multiple terabytes of storage.

 

[Helznicht]

&quot;exponentially? umm no its just times 2, i wouldnt call that &quot;exponential&quot;

If you just added a second drive &quot;WITHOUT&quot; raid, you would increase your data loss chance by x2. But neither drives data is dependent upon the others. If you lose a drive you still have half your data.

On raid, loosing one or the other = total data loss. Its more than a x2 chance here. Its not a simple math solution, but 2 raided drives have a higher percentage of data loss than twice that of a single dive.

 

[Kwad Guy]

I would never use Raid 0 unless

1) There is no critical data on the Raid 0 drives

or

2) You are doing regularly scheduled backups to another drive/other
media. If there IS critical data on the Raid 0 drives, I'd
set it up with a good DDS or DLT or AIX tape backup and good automated
backup software so that if/when the Raid 0 dies, you're all
set.

Of course, for the cost of good backup software and a good backup
system you could alternatively buy some more drives and go for
a striped and mirrored RAID setup, which would mean you'll never
lose data unless an absolute catastrophe occurs (e.g. you're
struck by lightning). Oh, and REAL raid like this requires
a REAL (read: SCSI) raid card, not a $20-50 IDE raid solution.

Sure, you can just live dangerously. I have done that. But only
on machines where I understand I might, at any time, lose everything
I have without any chance for recovery. Unlike a single non-raid
drive setup, data recovery programs don't work with failed raid
arrays...So if you lose a Raid drive...goodbye, good luck, and thanks
for all the fish.

Kwad

 

[obsidience]

<< OK ..let me throw this question into the mix. I have a RAID 0 setup with two 30GB drives. I went out an bought Ghost 2001 to help curb the possibility of losing by data. I open the book and it states that Ghost will not work with Raid 0 arrays.

So, is there a program that will work with striped arrays?

REX >>



Yes there is... Windows 2000 verifies file integrity on the fly and if there is a disk error it will mark the sector as bad and move the file elsewhere.

I'm not currently running RAID0, but for about 6 months I was using it on a KT7-A Raid mobo with 2x46Gig IBM 7200's on WIN2K, never had a problem.

But I kept all of my important data backed up on separate computer.

 

[Muadib]

Doesn't anyone do backups anymore?

 

[Recneps]

<<On raid, loosing one or the other = total data loss. Its more than a x2 chance here. Its not a simple math solution, but 2 raided drives have a higher percentage of data loss than twice that of a single dive.>>

No!! they have the same percentage loss as a single drive. Fact a single Hard drives will fail, Fact 2 single hard drives will fail when not in raid, Fact a RAID 0 array will fail. They all have one thing in common data loss is 100%.

Think of hard drives as dice:
You buy one hard drive it is not in a RAID array == rolling one die.

You buy two harddrive and use them in RAID 0 == rolling two dice, data will be lost based on the lowest value rolled.

You buy two harddrive and use them in a RAID 1 array == rolling two dice, data will be lost based on the highest value rolled.

 

[Kwad Guy]

It works like this:

If one drive has a 5% chance of failing within a specified period,
then the chances of it not having a problem within that period
are 95/100. If you have two identical drives, then the chances that
NEITHER drive will have a problem within that same specified period
is (95/100)*(95/100) = 9025/10000. Or, in other words,
your chances of a failure within the same period
have almost (but not quite) doubled (95/100 vs. ~90/100).

Now, in the real world, chances of a failure are pretty small.
So twice small is small. But it's still two times...So you need
to make a judgement call based on your own requirements, what
kind of data you're working with, how often you back up the data,
etc.

Kwad