Curing the long distance blues

Now is the time to rejoice! I enabled ‘ISL R_RDY’ mode on the four ISLs between sites, enabled long distance with sufficient buffer credits for 30km at full packet size (my links are either 16km or 18km, depending on who I’m talking to) and sat back to watch the portperfshow. I thought I was going to wet my pants when I saw the speed on each link leap from 60mb/s to 150! I reset the port stats, and noticed that I was still getting a number of ‘out of buffer credits’ errors. I’m not sure if I can get stats on the average packet size going through (can anyone advise?), so I took a stab and increased to 40km and reset the stats again. My self pleasure went into overload as the speed topped 170mb/s!

To get a tape copy to run from the remote site to production, we deleted a couple of copy pool volumes in TSM and re-ran a copy storage pool with multiple drives, so I had tape traffic going in both directions, and soon the throughput was topping 200mb/s!

For once, I am happy, and needed a good hosing down to calm myself. I just need to get some long distance licences for the 4100s I have spare so I can move the other site links (we have a second remote site linked to another machine room) from the creaking 12000s and I will be truly joyful.

On the home front, so far there have been no further steaming gifts left in the living room, just the odd puddle!