You should not have to start parity protection on the external disk.  

IIRC on the EMC the disk showed up as unprotected 9337 drives.  On the
ESS-800 we are using here the drives show up as 2105 drives with
Protection=Device Parity, even though we did not start Device Parity on them
from the iSeries.  All of the capacity is useable.

The UDFS considerations do add some complexity.  You'll need to mount the
UDFS after every IPL, and you'll need to take it into consideration when you
plan your backups.  If it is mounted it will get backed up with the
directory it is mounted to in your SAV (and /dev/QASP0x/yournamehere.UDFS
will get an "object in use" message.)  If it is not mounted
/dev/QASP0x/yournamehere.UDFS will be saved as a single object.  If you use
the EMC backup product you can back it up on your SAN and omit both the
directory and /dev/QASP0x/yournamehere.UDFS from your SAV.


Scott Ingvaldson
AS/400 System Administrator
GuideOne Insurance Group

-----Original Message-----
date: Thu, 18 Mar 2004 13:03:41 -0500
from: "Walden H. Leverich" <WaldenL@xxxxxxxxxxxxxxx>
subject: RE: SAN Attached to iSeries - Anyone?

>But once you've defined a bunch of 'small' drives, won't OS/400 
>simply dump them into the (designated) ASP, and make them available 
>as part of the Single Level Store? 

Yup. Of course the annoying thing is that I have to define a UDFS to
allow IFS to use the storage if it's not in the system ASP. 

>IIRC, there was talk about the 'problem' of dealing with OS/400 and 
>SANs-- OS/400 takes all the space available to it and adds it to the 
>S.L.S., which is not the way PCs work-- PCs grab space as needed.

PCs do the same thing as the iSeries. If I define 10 LUNs (logical
drives on the SAN) at 100G each I've "used" up 1TB of that SAN. It
doesn't matter if I store 1TB of data on that space or 1 byte of data,
it's committed to the machine that mounts the LUNs. Of course, if I only
needed 100G I'd only mount one LUN and then come back later and mount a
second when I need it. But that's no different than adding drives to the
iSeries as needed.

Of course, the thing I don't get is RAID on the SAN. The SAN redbook
html?Open) seems to imply that I would start parity protection for the
"drives" so that OS/400 RAID-5s them. That makes no sense to me since
most larger SAN units take responsibility for RAID themselves at the
hardware level (under the LUNs)


Walden H Leverich III
President & CEO
Tech Software
(516) 627-3800 x11

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