Disk Pool Contents

This page describes the contents of a dCache disk pool.

dCache disk pool filesystems contain the following:

[root@dcache log]# ls /export/raid01/pool/
control  data  setup  setup.orig  setup.temp

The setup file holds information about the configuration of this disk pool such as its maximum size and how it interfaces with an attached HSM (if such a feature is enabled).

The data directory contains the actual data that the dCache stores:

[root@dcache pool]# ls data/
000100000000000000001A78  00010000000000000002A6C8  00010000000000000004DAB0
000100000000000000001C20  00010000000000000002A6D8  00010000000000000004DCF0
000100000000000000001C30  00010000000000000002B1C0  00010000000000000004DF90
000100000000000000001C40  00010000000000000002B390  00010000000000000004E278
000100000000000000001C50  00010000000000000002B490  00010000000000000004E608

Corresponding to each PNFSid in the data directory, there should be two entries in the control directory:

[root@dcache pool]# ls control/
000100000000000000094E18  SI-000100000000000000094E18
000100000000000000095B68  SI-000100000000000000095B68
000100000000000000096EE8  SI-000100000000000000096EE8
000100000000000000096F18  SI-000100000000000000096F18
000100000000000000096F30  SI-000100000000000000096F30

The file with the same PNFSid as the data file contains one of the following entries

• cached - this means that the file in this pool is a cached copy of the original file that exists elsewhere in the dCache system.
• precious - this copy of the file is the original copy and should not be deleted by the system.
• receiving.cient - this indicates that that the dCache thinks that data is still being received from the client for this file. In reality the transfer probably never completed.

The contents of the files with the names SI-PNFSid are serialized java objects, containing the dCache storage information about the file, i.e.:

size=1055162368;new=true;stored=false;sClass=myStore:STRING;cClass=-;hsm=osm;
StoreName=myStore;store=myStore;group=STRING;bfid=<Unknown>;

You will only be able to read this information by running

java -classpath /opt/d-cache/classes/dcache.jar:. DumpSI /path/to/SI-file

after you have compiled the DumpSI.java code and placed the class file into /opt/d-cache/classes. The DumpSI.java code (if not already in the dCache distribution) can be found in the user-forum. The same storage information can be found via the dCache admin interface in the PnfsManager@PnfsDomain using the command:

storageinfoof PNFSid