Last modified 3 years ago Last modified on 01/12/16 14:51:16

dCache Tier I meeting January 12, 2015

[part of a series of meetings]

Present, IN2P3(), Sara(), Triumf(), BNL(), NDGF(), PIC(), KIT(), Fermi(), CERN()


(see box on the other side)

Site reports


Things are OK now

There are two disks that have failed --> IOException. Small pool for Tier-2

If you mark file as broken and a pool is restarted then the file will be OK.

From admin interface you can remove the "broken" bit.

New heardware for pool; deploying with CentOS 7.


Had an "Interesting" Christmas.

Alice pools dying under heavy load. These 80 TB ZFS; this is very slow for dCache. Alice fills these disk with small files. Have got the pool start-up from 6--8 hours down to 1 hour.

A lot of different things. Ulf guesses the average file size 50--100 MiB.

ZFS IOPS depends on the slowest disk in the system. Alice does a lot of xrootd vector reads; most less than 1 kiB in size. The block size is 256 kiB. Checksumming means this is very bad performance.

At DESY we tried Linux ZFS on Linux the performance was unpredictable and after a week

Planning to switch from ZFS to XFS during down.

News section of webpage needs updating.

Book: 2.13 2.14 links are broken.


Everything is running just fine.

Support tickets for discussion

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Same time, next week.