ADSM-L

Re: 3590 (E or H) drives per FC interface (6227) ???

2002-12-31 12:31:52
Subject: Re: 3590 (E or H) drives per FC interface (6227) ???
From: Orville Lantto <orville.lantto AT DATATREND DOT COM>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Tue, 31 Dec 2002 11:09:43 -0600
The sustained write rate of a 3590 drive is 15 MB/sec at the head.  You
multiply 15 times your compression ratio to get the sustained transfer
rate through you adapter.  I have saturated the arbitrated loop (FC-AL) of
a fibre 3590 with DB2 backups (60 MB/sec), but that was highly
compressible data.  The real question is: what are the requirements of
your environment?  If you need the full read/write capacity of your drive
for backups and/or restores, and you compress highly compressible data at
the drive, and you can actually generate that much I/O in your system,
then 60 MB/sec of bandwidth is needed per drive.  If your cards are
attached to a switch, they have 100 MB/sec. maximum bandwidth, so each
card can sustain 1 2/3 drives at saturation.

It is difficult to push data as fast as a 3590 can take it.  The client
disk and CPU will likely limit your ultimate throughput.  The best I have
yet attained was 114 MB/sec to 3 3590 E drives with DB2 reading from two
Sharks and transferring the data over an SP switch.  The switch was the
limiting factor, but the Winterhawk II DB2 node was nearing its CPU limit
(4 CPUs).



Orville L. Lantto
Datatrend Technologies, Inc.  (http://www.datatrend.com)
IBM Premier Business Partner
121 Cheshire Lane, Suite 700
Minnetonka, MN 55305
Email: Orville.Lantto AT datatrend DOT com





"Cook, Dwight E" <DWIGHT.E.COOK AT SAIC DOT COM>
Sent by: "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>
12/31/2002 10:35 AM
Please respond to "ADSM: Dist Stor Manager"


        To:     ADSM-L AT VM.MARIST DOT EDU
        cc:
        Subject:        3590 (E or H) drives per FC interface (6227) ???


I've looked through the archives and can't find much.
I've waded through IBM's web sites and can't find specifics...

Has anyone found any recomendations on max number of 3590's (FC attached)
per FC card on host ?

Environments I'm  looking at are 7017-S70's that have a max of 4 FC cards
(6227's) per system.
I'm already driving my ESS storage with 2, that would leave me with 2
cards
to drive 8 tape drives.
(or maybe mix everything together and let the device drivers balance the
loads ????)

So is anybody driving 4 3590's off a single FC adapter and if so how are
your data transfer rates look with 1, 2, 3 & all 4 drives running ?????
Math says
        1Gb (1024Mb/sec) FC card is 128 MB/sec or 450 GB/hr
        100 MB/sec burst data transfer rate of 3590 is 351 GB/hr
so really 1 card per 1 drive but 4 cards could drive 5 drives...
NOW...
With 3590-B1A's & E1A's that are SCSI attached (one drive per one scsi
adapter) I see migrations run at
B1A'a 22-ish GB/hr
E1A's 32-ish GB/hr
Now SCSI attached drives have a burst rate of 40 MB/sec 140 GB/hr
So on my E1A's I see migrations run at 23% of the burst rate

So if I expect the same from FC, migrations across FC would be at 23% of
100
MB/sec or 23% of 351 GB/hr or 80 GB/hr if I have one drive per one FC
card...

So with all that said, a single FC adapter should be able to drive five
and
a half (5.5-ish) FC 3590-E1A's or H1A's and run at least as good as SCSI
attached at a one-to-one atachment... right???

Anyone have any thoughts...
(other than I need a vacation)

Dwight E. Cook
Software Application Engineer III
Science Applications International Corporation
509 S. Boston Ave.  Suite 220
Tulsa, Oklahoma 74103-4606
Office (918) 732-7109

<Prev in Thread] Current Thread [Next in Thread>