You're getting confused between tape drive speed and channel speed.
The IBM 3590 E and H drives will read/write to the tape at a rate of 14 MBs.
Multiple that rate by your compression rate, if you have compression turned on.
The FICON channel, can operate at 200 MB or 270 MBs (on a z/890).
So if you had 2:1 compression, you would see a transfer of 28 MBs.
Uncompressed it will be 14 MBs at best.
And that is what you are seeing.
These are data streaming drives. You have to feed the beast. If your source
(disk) can't keep up with the tape drive and it's compression, you will see
much, much lower transfer numbers.
Tom Duerbusch
THD Consulting
>>> "Hughes, Jim" <jim.hug...@doit.nh.gov> 6/1/2009 1:08 PM >>>
We have Z/VM 5.4, with 4 3590's attached to the z890 using FICON Express
with the 2-Gbps feature. The tape controller is the A60.
I am doing some tape speed tests and my results are not very good. I
have a pipeline(look below) that writes 65,500 byte blocks to the 3590.
I used the cms command TAPE MODESET ( NOCOMP/COMP to turn compression
off/on.
I see around 14 MB/sec with compression off and 28 MB/sec with
compression on.
The 3590 Planning manual says the 3590's should operate at 200MB/sec
when using FICON with the 2-Gbps feature.
There maybe a problem with my pipeline or my expectations.
Here is the pipeline. Any insight or suggestions are welcome.
/* */
arg blkcnt .
if blkcnt = "" then exit 99
numeric digits 12
"TAPE REW"
"TAPE FSF"
say time()
x = time("E")
"PIPE literal <------------> | >> tapetest 3590 a"
"PIPE (endchar ?) ",
"? xrange 00-ff |", /* 256 characters*/
" dup 256 |",
" specs todclock 1 1-* n |",
" join 256 |", /* 64k */
" dup * |",
" specs todclock 1 1-* n |",
" fblock 65500 00 |",
" take " blkcnt " |",
" cnt: count lines |",
" tape 181 |",
" specs 1-1 1 |",
" join 4999 |",
" specs todclock 1 |",
" dateconv 1.8 todabs ISODATE timeout |",
" specs recno 1 ",
" substring fs . f 1 of word 2 nw ",
" /5,000 Blocks Interval Check/ nw |",
" console |",
" >> tapetest 3590 a ",
"? cnt: | var xblkcnt | specs / Blocks written =/ 1 w 1 nw |",
" console"
____________________
Jim Hughes
603-271-5586
"It is fun to do the impossible."
