ADSM-L

Re: AIX Server Configurations

1998-09-21 16:25:34
Subject: Re: AIX Server Configurations
From: Dwight Cook <decook AT AMOCO DOT COM>
Date: Mon, 21 Sep 1998 15:25:34 -0500
     Well, uhmmm...
     fast wide diff scsi-2 is roughly 70 GB/hr (20MB/sec) TOTAL TRAFFIC
     I've run 3590's at very close to IBM's rating of 31GB/hr (I've hit
     30GB/hr)  Now granted that 2*30=60 (<70) BUT you can't be sure that
     one process will only be ready to write in the dead spell of another,
     yada, yada, yada so from my testing I agree with what I've heard from
     others in the past that...
     1-FWDiffSCSI2 & 1-3590 -> 30GB/hr total
     1-FWDiffSCSI2 & 2-3590 -> 45GB/hr total
     1-FWDiffSCSI2 & 3-3590 -> 52GB/hr total
     that is, for each additional drive you chain on the controller you see
     50% (of previous rate increase) increase...
     in other words,
     you add 1 drive you get 30GB/hr
     you add a second you get 30+(30*.5)=>30+15=>45
     you add a third you get 30+15+(15*.5)=>30+15+7.5=>52.5
     you add a 4th you get 30+15+7.5+(7.5*.5)=>30+15+7.5+3.75=>56.25

     The most drives we have on a single adsm environment is 8.
     The most in a single ATL is 16 (used by 2 adsm servers)
     We run 2 drives per adapter in these environments...
     Since you never can be 100% sure of how adsm is going to grab drives
     if you put 3 drives per adapter you might have ADSM running 3 tape
     tasks and using all three on the same adapter card (yielding
     52.5GB/hr) where if you put two per adapter it would have to at least
     grab drives across two adapters which would yield 45+30GB/hr or
     75GB/hr... and yes, this will vary across activities performed against
     those tapes.

     later,
           DWight


______________________________ Reply Separator _________________________________
Subject: Re: AIX Server Configurations
Author:  pricerr (pricerr AT westinghouse DOT com) at unix,mime
Date:    9/21/98 2:53 PM


Sherry,

You may want to consider putting 2 (or even 3) 3590 drives on each SCSI.
From what I have found, the SCSI channel can drive two 3590 drives at full
speed.  ADSM seldom can even drive the 3590's that fast!



> ----------
> From:         Sherry Jackson[SMTP:Sherry.Jackson AT TORO DOT COM]
> Sent:         Monday, September 21, 1998 3:31 PM
> To:   ADSM-L AT VM.MARIST DOT EDU
> Subject:      AIX Server Configurations
>
> We are running an AIX server with a 3494 library attached with 6 3590
> tape drives in it.  We will be purchasing 4-6 more tape drives in the
> future inside another unit.
>
> The problem we are having is the i/o slots in the RS/6000's.  The S70 is
> the only machine that can go over 15 slots, at least in the latest book
> we have.  With 10-12 tape drives, two ethernet, one ATM, one fddi and
> SSA disks attached, you can see will need at least 15 slots.
>
> Do any of you have 10+ tape drives attached to one machine and if so,
> what is your configuration?
>
> Sherry Jackson
> The Toro Company
> Bloomington, MN
>