Re: more DASD!!!

[Larry Bolhuis <lbolhuis@xxxxxxxxxx>]

Dan,

 The 4G drives are not supported on the new hardware unless your
existing system is converted as a migration tower. Model 400s cannot be
migration towers so the drives will be yours to keep. Many of them are
simply too big to fit anyway. 

 They are cheap enough used to buy 'em and dump them when done.

 Doug did an excellent job of outlining your options. To answer his one
unknown, yes you can have multiple mirrored pairs Plus RAID. So now you
get to 'pay your money and take your choice'!  

 - Larry

Douglas Handy wrote:
> 
> Dan,
> 
> >Is the maximum counting only the "usable" mirrored DASD or the total DASD
> >regardless of mirroring?
> 
> It is the maximum of 4 drives on the FSIOP plus 8 drives in the 7117 expansion
> feature.  Twelve drives at 4.19 each gives about 50.3GB (max unprotected).
> 
> On your box, the FSIOP drives cannot be part of a RAID set, so those should 
>both
> be mirrored pairs.  On the 7117, you can put all 8 drives in a RAID set, so 
>the
> maximum protected DASD you can reach is:
> 
>   2 x 4.19 =   8.38  mirrored drives in the FSIOP
>   7 x 4.19 = 29.33  effective usable area of RAID 8 drive set
>                   ----------
>                    37.71 GB maximum protected DASD
> 
> Using all mirrored pairs, you'd be reduced to 6 pairs @ 4.19 = 25.14GB or so.
> 
> In your current case, you can either add 4 drives in a RAID set, increasing 
>your
> DASD by about 12GB, or you can change the 4 drives in the 7117 to be part of a
> new RAID set.  RAID sets need at least 4 drives per set, and the 7117 only has
> room for 8 drives but they could all be in the same set.
> 
> I know the 6502/6522 controller you'd have in the 7117 can handle two RAID 
>sets.
> I am not sure if it can do two mirrored pairs *plus* a RAID set.  So it may 
>not
> be possible to add a RAID set and leave the existing 4 drives mirrored.
> 
> OTOH, without even buying another drive you could convert the 4 mirrored 
>drives
> (in the 7117) to a RAID set and pick up another 4.19GB usuable space, which
> gives you a 25% boost in capacity without buying more drives.  And you'd still
> be protected from drive failures.
> 
> The 400-2133 does not have hot swappable drives anyway, and for a machine 
>likely
> to  be retired within a year I'd convert to RAID and add only as many drives 
>as
> you need.  For example, buying one more 6607 and converting to RAID will give
> you a 50% increase in protected DASD from your current config.
> 
> >A concern was raised that whatever additional DASD we buy today for this old
> >box might not be migratable to any new iSeries system we acquire in the
> >future.  Is that a real concern?
> 
> I *think* support for the 6607 drives is going (has gone?) away on newer 
>models.
> 
> But the newer drives are faster anyway.  The 6607's aren't expensive enough to
> warrant taking to the next machine when you only have 8-10 of them.
> 
> IMHO.
> 
> Doug
> 
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-- 
Larry Bolhuis           | Cogito ergo mercari iSeries 
Arbor Solutions, Inc.   |
(616) 451-2500          |               (I think, therefore I buy iSeries.)
(616) 451-2571 -fax     |
lbolhuis@arbsol.com     |        #3  1951-2001
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