What trouble have you had connecting more than one 3590 to a SCSI
controller? We use 8 3590s connected to 2 controllers, also on a wide SP
node and have no problems. We are using fast, wide SCSI. In theory it
would be possible to use nearly all the (20Mb/s) bandwidth of the SCSI
with 2 3590s (9Mb/s) but in practice this does not happen as ADSM cannot
drive the tapes that fast.

In message <852722369.109917.0 AT tipper.demon.co DOT uk>, "Alan R.White"
<arw AT TIPPER.DEMON.CO DOT UK> writes
>Has anybody ever run multiple AIX ADSM servers all working with one 3494?
>We're running the server on an SP wide node and have managed to shoehorn 4
>SCSI controllers in for the 3590 drives in the library. We've still got
>more client machines to migrate to ADSM and some of them have large volumes
>of data to backup so 2 more 3590s have arrived. Problem is we know from
>past experience that its just not worth putting more than one 3590 on a
>SCSI controller.
>
>The only answer we can come up with is to run a second ADSM server on
>another node with adequate MCA slots free for the SCSI connections to, say,
>the two new 3590s in the library and start putting clients onto this one.
>This will bring more administration overheads for us and some possible
>areas of confusion. Can anyone see any other problem areas running these
>two ADSM servers against a single 3494, containing 6 3590 drives, two of
>which are managed by one server, four by the other?
>
>We're doing what we can to minimise tape drive contention but contention
>does exist and hence the need for more drives. Anyone any experience of
>running ADSM on a high-node? These have 16 MCA slots and would allow us to
>continue with one ADSM server but we've heard that the high-speed switch
>code doesn't perform well on an SMP machine.
>
>Thanks in advance
>Alan White

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