Rsync to remote host much faster than 10k/sec speeds on local rsync

[W Smith]

Thanks for the reply. The filesystems are on different disks on the
same machine.

I should have mentioned in my original post that the transfer works
for a while then hangs. I've read on the rsync page to run an strace
and here are the results, just before the hang occurrs:

select(5, NULL, [4], NULL, {60, 0})                               = 1
(out [4], left {60, 0})
write(4, "\0\200\0\0", 4)       = 4
select(5, NULL, [4], NULL, {60, 0})                               = 1
(out [4], left {60, 0})
write(4, "\"src/dir/filename.."..., 32768)       = 32768
select(5, NULL, [4], NULL, {60, 0})                               = 1
(out [4], left {59, 999000})
write(4, "\0\0\0\0", 4)       = 4
select(5, NULL, [4], NULL, {60, 0})                               = 1
(out [4], left {60, 0})
write(4, "\223\316\\\340\23\4F\33\f\306t\1\251\202\25\22", 16)       = 16
munmap(0xb2958000, 266240)                               = 0
close(3) = 0
select(6, [5], [], NULL, {60, 0})                                = 1
(in [5], left {60, 0})
read(5, "\32\0\0\t", 4) = 4
select(6, [5], [], NULL, {60, 0})                                  = 1
(in [5], left {60, 0})
read(5, "src/dir/\n", 26) = 26
write(1, "src/dir/\n", 26) = 26
select(6, [5], [], NULL, {60, 0}) = 0 (Timeout)
select(6, [5], [], NULL, {60, 0}) = 0 (Timeout)
select(6, [5], [], NULL, {60, 0}

The hangs can last 5-10mins+ with the same above timeout lines
repeating over and over at maybe 2min intervals before finally
continuing.

I don't know if this additional information helps diagnose the problem
at all, I've spent all day trying to find a solution to no avail.