Re: RAID arrays with different size disk units?

James W Kilgore wrote:

> Technically there is no reason that a 4 GB drive could not support two 2 GB
> drives, but logistically it may more work than it's worth.  In this case you
> would have the two 2 GB drive support the one 4 GB drive and how would they
> determine which drive gets which half?

Actually this would not be correct.  Since a RAID set can maintain it's 
integrity 
with only a single failed drive, the singe 4GB drive acting like 2 2GB units 
would 
not work.  So long as that drive was functioning it would appear OK (albeit 
slower 
since it would get double the work) but if it failed there would be TWO drives 
missing from the array.  So long data.....

-- 
Larry Bolhuis         |
Arbor Solutions, Inc  | Two rules to success in life:
(616) 451-2500        | 1. Never tell people everything you know.
lbolhui@ibm.net       |

> Keep it simple.
> 
> James W. Kilgore
> email@James-W-Kilgore.com
> 
> Neil Palmer wrote:
> 
> > They need to be the same capacity drives.
> >
> > Neil Palmer         DPS Data Processing Services Canada Ltd.
> >                                              AS/400~~~~~
> > Markham,  Ontario,   Canada    ___________          ___  ~
> > Phone: (905) 474-4890  x303   |OOOOOOOOOO| ________  o|__||=
> > Cell.: (416) 565-1682  x303   |__________|_|______|_|______)
> > Fax:   (905) 474-4898          oo      oo   oo  oo   OOOo=o\
> > mailto:NeilP@DPSlink.com    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > http://www.DPSlink.com        AS/400  The Ultimate Business Server
> >
> > -----Original Message-----
> > From:   Sclind2@aol.com [SMTP:Sclind2@aol.com]
> > Sent:   Wednesday, December 16, 1998 6:15 PM
> > To:     MIDRANGE-L@midrange.com
> > Subject:        RAID arrays with different size disk units?
> >
> > Are there any circumstances where disk units of a different size can be 
>added
> > to an existing RAID array?  The Backup and Recovery manual states that you
> > need 4 disk units of the same size to start RAID protection, and that
> > additional units can be added later.  But it is unclear whether these need 
>to
> > be the same size units.
> >
> > I currently have one RAID array that isn't full; it has four 2gb drives (raw
> > size).  Can I add 4gb (or larger) disk units into this array?  We have added

> > disk units into an existing array in the past, but they have always been of
> > the same size.
> >
> > If this can be done, what is the resulting usable size of the new units?  In
> > the above case, establishing RAID protection ended up leaving us with four
> > units of 1475mb each.  (I.E., 25% was used on each of the four units).
> >
> > Scott Lindstrom
> > Zenith Electronics Corp
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