[Ham-Computers] RAID 1 Questions

[WA5CAB at cs.com]

Jim,

RAID 1 is a mirrored array of two or more drives.  The same data is written 
to all drives at the same time (at least if the array is implemented in 
hardware).  The total capacity of the array is equal to the capacity of the smallest 
drive in the array.  Generally, unless you have to use a larger drive in a 
pinch in order to rebuild the mirror, it's most common to have all drives the 
same.

Most common in consumer level (cost) equipment is to use two drives if using 
RAID 1.

The benefit of RAID 1 is that if you have a drive failure there is no data 
(or performance) loss so long as one drive continues to work.  The computer I'm 
using here has C and D drives as RAID 1, two drives each.  Not long after I 
set it up, I did have a drive failure on C (first one in years).  As this setup 
is not hot swappable, I had to shut down to replace the drive but didn't lose 
anything and maybe more importantly, didn't have to reinstall the OS and 
applications.

The purpose of backup (like Ghost) is not the same as the purpose of RAID.  
They don't protect against the same things.  Depending upon the RAID level (0, 
1, 5, 1+ 0, etc.) the purpose of RAID is to (a) keep the equipment up and 
running if a drive (sometimes more than one drive) fails or (b) to increase the 
logical size of a drive beyond the capacity of currently available single drives 
or (c) both.  Some vendors have also claimed performance improvement (faster 
throughput) but at least at the consumer level, independant tests don't 
usually agree.  But RAID provides no protection against corrupted or deleted data 
(files) or physical damage to or theft of the entire setup.  That's what backups 
are or can be useful for.

As for why you couldn't add an extended partition, I don't have an answer as 
I don't know whether your RAID 1 array is implemented in hardware (using a 
dedicated controller, as the machine here does) or in software where the main CPU 
has to do all the work.  In the former case, the OS does not know (usually) 
that it is talking to an array instead of a single drive so you should be able 
to do anything to the array that you could do to a single drive.  In the 
latter case, I've no idea as I've never run one.

And finally, if Ghost 10 runs OK and was useful to you, and you still have 
the original CD in case you should have to reinstall it, whether Norton still 
supports it or not is in my opinion immaterial.  Over the years, I would guess 
that 1/3 of all commercial software that went to a newer version didn't add 
anything useful and didn't fix any older problems.  I'm still using Ghost 9, for 
example.  More than once over the years, I bought a new version of something, 
installed it, didn't like it, and went back to the earlier one if I could.

In a message dated 10/25/2008 11:10:50 AM Central Daylight Time, 
JJan-3 at cox.net writes: 
> How do you use RAID 1?   I Googled RAID 1, and understand it backs up 
> your C drive to a second internal drive of the same size.  Does it 
> run automatically, or do is there a menu somewhere?  If you need to 
> recover, what do you do?
> 
> My Dell E510 is set up for RAID 1 - I'm not sure why since it came 
> with Norton Ghost 10.  It has the option to return to original 
> factory settings if F12 is pressed during startup, the app. and image 
> are on their own "drives" and the RAID configuration may be provided 
> so the user won't tamper with them.  I wanted to add an extended 
> partition and was unable to do so.
> 
> I'm having problems with this computer (not shutting down properly, 
> not printing, etc.) and am thinking of installing a new drive and 
> making a clean installation, and am wondering whether to use the RAID 
> 1 configuration.  Norton Ghost 10 is no longer supported by Symantec 
> so I'll probably not use it.
> 

Robert Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480
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