The Quiet Before CHEP...

Blog posts have been a bit thin on the ground this week, both because of GridPP 19 and the sense that CHEP was looming and the poster had to get done and the paper had to get written.

Well, after a few delays and some severe jet lag I did arrive and with a poster too. If you want a quick preview I put the poster's pdf on the web.

Weather is good, but my phone can't find a network, so don't try calling!

Grieg re-testing DPM 1.6.3 rfio

Thanks to Greig for retesting our DPM 1.6.3's rfio.

The good news is that the code changes from 1.5.10 drastically reduce the number of rfio_open() failures. These now only crop up at about 70 clients (all within 1 second). The average open time is also much more stable, never rising above 2.5s.

However, we now see a problem with io wait on the disk server, and the total LAN rate struggles to reach 200MB/s, where as 1.5.10 easily reached 400Mb/s.

This remains to be investigated, but the only change on the disk servers is the update of DPM version, so I think it must be a DPM issue.