On Fri, Aug 14, 2009 at 20:10, Pat Barber<mboceanside@xxxxxxx> wrote:
Doing a data transfer "does not" cause a CPU to be
bound.

CPU bound = limited by CPU. Which is what you see on the very small
machines when doing large NFS or FTP transfers (100% CPU load caused
by the FTP process).

A very narrow data path with limited memory causes
the process to be slow but the processor is doing
VERY little work.

Gigabit Ethernet is 125 Megabyte/s. Significantly more than the IBM i
entry level tape drive, the DAT72. It is rated at 3 Megabyte/s.

SLR60 2.5" drives are rated at 4 Megabyte/s, which is what most of the
Power 520 i've installed back then shipped with.

Most model 170ies had a 100mbit/s NIC, which can provide up to 12.5
Megabyte/s, which is significantly more than the MLR3 had (2
Megabyte/s).

The data path is the restriction. Doing massive copying
on a network of twisted pair is both slow and silly.

It's slower than LTO4, i'll give you that (LTO4 is 120 Megabyte/s
uncompressed, but through compression up to 240 Megabyte/s may be
achieved).

Most any tape drive made in the last 10 years is
much faster than a "network transfer".

No, only high-end, high-performance tapedrives like the LTO line of
products are fast. Most other tape options are rather slow, though
some of them can beat 100mbit Ethernet.

Your comments on the speed of older machines shows a
real lack of experience in these computers.

Well, i'll give you that. I've mostly migrated away from these
machines or had to debug issues.


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