[DM-MUG] backups, external FW drives, and concatenated RAID

[Michael R. Hoffmann]

No, but you will be limited to the size of the smaller one.

On Mar 27, 2007, at 11:06 AM, Ray Bowler wrote:

> I'm trying to remember but don't the two drives in the RAID have to  
> be the same size?
>
> At 10:29 AM -0500 3/27/07, Bryan Baker wrote:
>> You might also be able to use another RAID feature to mirror the  
>> 500 to the 250's. Not too sure if that'd work right though.
>>
>> RAID 0 = Striping - Faster, but no redundancy, so loss of 1 drive  
>> is catastrophic.
>> RAID 1 = Mirroring - As the name implies 1 (or more) drives mirror  
>> the other - 100% redundant, but you loose capacity.
>> RIAD 5 = Striping with parity - common, but popularity is fading,  
>> more reliable than 0, but less than 1.
>>
>> There are lots of other permutations and variations, but those are  
>> some of the more common.
>>
>>
>> On Mar 27, 2007, at 8:54 AM, Darcy Baston wrote:
>>> Sure!
>>>
>>> Here's what my archive setup was before:
>>>
>>> 1 Firewire HD 250GB (in use)
>>> 1 Firewire HD 250GB (backup of other)
>>>
>>> Here's what I have now
>>>
>>> 1 Firewire HD 500GB (in use, what I bought just recently)
>>> 1 RAID  (1 Firewire HD 250GB + 1 Firewire HD 250GB) = 500GB,  
>>> mounts on desktop as one HD of 500GB (backup of other)
>>>
>>>
>>> Using the RAID features of Disk Utility, I told it to add the  
>>> 250GB capacity of one of the drives to the end of the 250th  
>>> gigabyte (relatively speaking) of the other, and mount it on the  
>>> desktop as one single 500GB drive. It's an illusion that there is  
>>> one drive of 500GB, when it's really just 2 drives of 250GB each.  
>>> "Concatenation" means "put the space of one at the end of the  
>>> other so when one fills up, spill over to the other, but only  
>>> ever show me one drive icon/device".
>>>
>>> That gave me a new pseudo 500GB drive. That left me with just one  
>>> device, and no backup drive for that new higher capacity pseudo  
>>> device, so I bought an external single 500GB drive. The new 500GB  
>>> single unit is the one I'm now using as the archive, and the RAID  
>>> Concatenated setup is the backup.
>>>
>>> This means I have 3 external hard drives. I'd love to go back to  
>>> two. If anybody wants to buy the 2x250GB drives, I'll gladly use  
>>> the money to put towards another single 500GB drive. :) They're  
>>> only 6 months old if anyone's interested.
>>>
>>> Darcy
>>>
>>> On Tuesday, March 27, 2007, at 06:57AM, "Victoria L. Herring"  
>>> <lists at herringlaw.com> wrote:
>>>>> I ran out of room on my external 250GB Archive drives (one source,
>>>>> one backup) this weekend. So I bought a new external 500GB WD  
>>>>> MyBook
>>>>> Firewire drive, and used OS X's Disk Utility RAID features to
>>>>> concatenate the two 250GB externals to act as the 500GB backup
>>>>> solution for the new 500GB drive.
>>>>
>>>> Darcy I really hate to sound stupid, and it IS early, but  
>>>> perhaps you
>>>> could explain to me what the value of a RAID is and what
>>>> concatenation is and why this is better than the two source and
>>>> backup drive system you had....the picture was a big help but I'm
>>>> missing some of the early explanation....
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>>
>> --
>> Bryan "ka-klick" Baker
>> Singer/Songwriter
>> With 2 New CDs!!! See my website for details
>> kaklick_mar... at mac.comhttp://ka-klick.com
>>
>>
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>
>
> -- 
> Ray Bowler
>
> rbowler.home.mchsi.com
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