RE: Any Experience with Data Transfer Rates to a 3590-H11

William,

Can you supply any information about the adapter you are using to connect
your tape drive.  If I recall correctly, the 740 would have originally
shipped with either a #6534 or a #2729.  A newer card, the #2749, will
support more throughput, but because both the #2729 and the #2749 meet or
exceed the rated capacity of the H11, this should not make a difference.

The rated maximum throughput for the original cards above is 14mb/sec
(uncompressed) which is the maximum throughput of that generation of SCSI
devices.  The 43MB/sec figure reflects the average three-fold
compression, which can vary depending upon the type of objects being
saved.

Some thoughts and questions:

Does your input/output adapter have a dedicated I/O Processor, or does it
share with other adapters?  If your tape adapter is on the same IOP as
the disk drive IOA, you could have a conflict which might lessen your
throughput at the IOP level.

The 740 should have enough processor muscle to drive your hardware fairly
close to its rated capacities.  On some smaller machines, the CPU just
can't present data fast enough to drive a 3590 at its rated maximums.

When you say that you get about 10MB/sec on controlled tests, is that a
measurement of raw data, or are you factoring in compression?

Can you describe your controlled tests?  Are you measuring only the
writing to tape, or does this include time for the system to prepare the
data for writing to tape?

Regards,
Andy Nolen-Parkhouse

> bounces@midrange.com] On Behalf Of William N. Harrell, Jr.
> Subject: Any Experience with Data Transfer Rates to a 3590-H11
> 
> Last week, we upgraded our 3590-B11 to the new H11.
> 
> We are getting the benefit of up to 180gig per 'K' Tape with 3:1
> compression, but we have not gained any data transfer rate speed.
> 
> The IBM annoucement said the H11 was 50% faster than the B11.
> 
> 
> ie:  raw transfer rate of 14mb/sec for the H11 vs 9mb/sec for the B11
> 
> The annoucement also states "up to 43mb/sec with 3:1 Compression.
> 
> On controlled tests, we are getting just around 10mb/sec data transfer.
> This is on a 9406/740.
> 
> What is everyone else seeing ?