CMS Tier-3 News Item

Scheduled downtime to upgrade dCache from version 2.2 to 2.6


On Friday 8th Nov at 12:00 we're going to upgrade dCache from version 2.2 to 2.6 DONE


dCache Upgrade

Because the several middlewares employed in the Grid are migrating towards a safer usage of the digital certificates based on the SHA-2 digests, it was requested to upgrade the T3 dCache /pnfs middleware to a newer version that's also designed to manage this new kind of certificates; we're accordingly going to upgrade the T3 dCache /pnfs middleware from the current version 2.2 to version 2.6 on Friday, November 8th starting at 12:00 until the end of the day. During that time interval the T3 dCache /pnfs middleware will be either not available or unreliable so please avoid to access it.

UIs middleware upgrade

We are also exploiting this downtime to upgrade the Grid middlewares installed on the t3ui0[1-9] servers to the latest UMD3 UI; the T3 users will be able to login and to work on the t3ui0[1-9] servers but please don't use the Grid commands like srmcp or lcg-cp because they're going to be upgraded; it's advisable to logout and to login again into the t3ui0[1-9] servers following the end of the downtime to avoid any error due to some outdated path to the new Grid commands. Also, don't submit any job involving the T3 dCache /pnfs middleware.

New Linux Groups

An other visible change will be the partitioning of the T3 users in the Linux groups:
  • ethz-ecal
  • ethz-bphys
  • ethz-ewk
  • ethz-higgs
  • ethz-susy
  • psi-bphys
  • psi-pixel
  • uniz-phys
  • uniz-higgs
  • uniz-pixel
the former global primary group cms is going to become a secondary group, e.g.:
$ id dmeister
uid=571(dmeister) gid=532(ethz-higgs) groups=532(ethz-higgs),500(cms)
The partitioning of the T3 users in the Linux groups:
  • will allow a faster and simpler understanding of the /pnfs space usage by leveraging on the new gid setting: having all the files assigned to cms always made this kind of accounting very tricky in dCache.
  • will allow to make accounting in the batch system also according to the new gid setting.
  • as a side effect, each new file written in /shome, /pnfs, /scratch, /tmp will be written with the new gid setting and this will prevent users from an other group to accidentaly delete your group writeable files/dirs.
  • it will allow the creation of dedicated "group dirs" in /pnfs where only your group can operate.
conversely the partitioning is not suppose to alter your daily experiences on the servers t3ui0[1-9], or on the computational servers t3wn[10-40]; kindly inform us if you will get issues there.

Following how the /pnfs will be modified by the partitioning:

$ ls -l /pnfs/ | grep -v cms 
total 56
drwxr-xr-x    2 alschmid     uniz-bphys 512 Feb 21  2013 alschmid
drwxr-xr-x    5 amarini      ethz-ewk   512 Nov  7 15:37 amarini
drwxr-xr-x   18 andis        ethz-bphys 512 Jan  5  2010 andis
drwxr-xr-x    2 arizzi       ethz-bphys 512 Sep 16 17:49 arizzi
drwxr-xr-x    5 bean         psi-bphys  512 Aug 24  2010 bean
drwxr-xr-x    5 bianchi      ethz-higgs 512 Sep  9 09:40 bianchi
drwxr-xr-x   30 bmillanm     uniz-bphys 512 Jan 17  2012 bmillanm
drwxr-xr-x   29 bortigno     ethz-higgs 512 Apr 18  2013 bortigno
drwxr-xr-x   98 buchmann     ethz-susy  512 Nov  5 20:36 buchmann

Final Remarks

There won't be any email announcing the beginning of the downtime, but we will send the usual email announcing its successful completion.

If you have a good reason to postpone all those upgrades kindly let us know asap and we will find an other day; the Grid asked us to upgrade by the end of 30th November.

If you're interested in the SHA-2 topic there is a good .pdf on the web, but it's pretty technical, the average CMS user can safely skip these details.

FabioMartinelli 8. 11. 2013

Title Scheduled downtime to upgrade dCache from version 2.2 to 2.6
Summary On Friday 8th Nov at 12:00 we're going to upgrade dCache from version 2.2 to 2.6 DONE
User FabioMartinelli
Date 8. 11. 2013
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Topic revision: r8 - 2013-11-09 - FabioMartinelli
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