ALICE native xrootd
Decommissioning ALICE native xrootd servers and dealing with data loss
Aim of this documentation
This objective of this document is to detail the procedure to follow by system administrators when they want to remove an xrootd server (decommissioning) or when they lost a filesystem on an xrootd server.
This document is based on the mails exchanged on the firstname.lastname@example.org list and on the real cases encountered at the GRIF-IPNO site. Costin Grigoras is the author of the different recommendations and tips successfully applied at IPNO.
A quick presentation of the xrootd files tree
On each xrootd server there are on or more disk partitions where the data files are stored. There is also a namespace which is a directory containing the names of the data files: theses names are the ones the redirector uses. The name itself is a symlink to the real data file. The name space can be in a separate partition or in a subdirectory of a data partition.
In the case of IPNO, the namespace is always a subdir of the first data partition.
- df -h|grep xrddata
/dev/sdb1 9.1T 5.6T 3.6T 62% /grid/xrddata1 /dev/sdb2 9.1T 5.6T 3.6T 62% /grid/xrddata2 /dev/sdb3 9.1T 5.6T 3.6T 62% /grid/xrddata3 /dev/sdb4 9.1T 5.6T 3.6T 62% /grid/xrddata4 /dev/sdc1 9.1T 5.6T 3.6T 62% /grid/xrddata5 /dev/sdc2 9.1T 5.6T 3.6T 62% /grid/xrddata6 /dev/sdc3 9.1T 5.6T 3.6T 62% /grid/xrddata7 /dev/sdc4 9.1T 5.6T 3.6T 62% /grid/xrddata8
- ls -ld /grid/xrddata1/namespace
drwxr-xr-x 18 xrootd xrootd 4096 Mar 30 2015 /grid/xrddata1/namespace