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Specialized NFS Dot Commands

The following commands provide information concerning a file’s locality, checksums and storage location.

GET LOCALITY

Returns the media types on which the file is currently stored.

USAGE:

cat ".(get)(<filename>)(locality)"

RETURNS:

  • ONLINE: stored on disk
  • NEARLINE: requires staging or data replication before open succeeds
  • ONLINE_AND_NEARLINE: stored both on disk and tape
  • UNAVAILABLE: not stored on any media (i.e., lost)

EXAMPLE:

$ cat ".(get)(test_file-Thu_Oct_23_10:39:37_CDT_2014-109)(locality)"
$ ONLINE_AND_NEARLINE

NOTES:

Currently, the NFS client sends ‘localhost’ to the poolmanager as its hostname (the protocol match defaults to ‘/’). SRM does something similar. In the future this may be modified to send the actual IP address of the client.

There are no guarantees concerning future availability of the file; in particular, ONLINE_AND_NEARLINE may revert back to NEARLINE at any time unless the file is pinned.


GET CHECKSUM TYPES

Get the valid / recognized checksum types for dCache.

USAGE:

cat ".(checksums)()"
RETURNS:

A new-line delimited list of checksum type names.

EXAMPLE:
$ cat ".(checksums)()"
ADLER32
MD5
MD4

GET CHECKSUM(S)

Get checksum types and checksums for a given file.

USAGE:

cat ".(get)(<filename>)(checksum[s])"
RETURNS:

A comma-delimited list of type:value pairs for all checksums stored in the database.

EXAMPLE:
$ cat ".(get)(test_file-Thu_Oct_23_10:39:37_CDT_2014-109)(checksums)"
$ ADLER32:66300001

SET CHECKSUM

Set a checksum value for a file. An ordinary user can only set one checksum (type, value) pair, and cannot overwrite existing values. A ROOT user is allowed to set multiple types (successively) and also to overwrite values for any type.

USAGE:

touch ".(fset)(<filename>)(checksum)(<type>)(<value>)"
EXAMPLES:
[arossi@otfrid volatile]$ touch testfile

[arossi@otfrid volatile]$ cat ".(get)(testfile)(checksum)"

[arossi@otfrid volatile]$ touch ".(fset)(testfile)(checksum)(ADLER32)(ffffffff)"

[arossi@otfrid volatile]$ cat ".(get)(testfile)(checksum)"
ADLER32:ffffffff

[arossi@otfrid volatile]$ touch ".(fset)(testfile)(checksum)(ADLER32)(fffffff0)"
touch: setting times of ‘.(fset)(testfile)(checksum)(ADLER32)(fffffff0)’: Operation not permitted

[arossi@otfrid volatile]$ ksu
Authenticated arossi@FNAL.GOV
Account root: authorization for arossi@FNAL.GOV successful
Changing uid to root (0)

[root@otfrid volatile]# touch ".(fset)(testfile)(checksum)(ADLER32)(fffffff0)"

[root@otfrid volatile]# cat ".(get)(testfile)(checksum)"
ADLER32:fffffff0

[root@otfrid volatile]# touch ".(fset)(testfile)(checksum)(MD5)(12341234123412345678567856785678)"

[root@otfrid volatile]# cat ".(get)(testfile)(checksum)"
ADLER32:fffffff0, MD5:12341234123412345678567856785678

PIN/STAGE

Allows users to pin or stage files.

USAGE:
touch ".(fset)(<filename>)(<operation>)(<duration>)(<unit>)"
OPTIONS:

operation can be replaced by:

  • pin
  • stage
  • bringonline

These are equivalent options.

duration must be 0 or a positive integer; 0 will unpin the file.

unit can be replaced by:

  • SECONDS
  • MINUTES
  • HOURS
  • DAYS

This argument is optional and defaults to SECONDS.

EXAMPLES:

Pin file for one minute:

$ touch ".(fset)(test_file-Thu_Oct_23_10:39:37_CDT_2014-109)(pin)(60)"

Pin file for two minutes:

$ touch ".(fset)(test_file-Thu_Oct_23_10:39:32_CDT_2014-418)(pin)(2)(MINUTES)"

Remove pins on the file:

$ touch ".(fset)(test_file-Thu_Oct_23_10:39:32_CDT_2014-418)(pin)(0)"

For further explanation of pinning, see Pinning Files to a Pool.


GET/SET TAPE LOCATION URI

Stores, retrieves and modifies the URI string(s) which define an HSM/tape location. A normal user can read and write once to this file. Root can overwrite and append as well.

USAGE:
cat ".(suri)(<file name>)"
echo [...] > ".(suri)(<file name>)"
echo [...] >> ".(suri)(<file name>)"
RETURNS:
cat will return a list of locations (there may be multiple ones).
EXAMPLE:
$ cat ".(suri)(data001)"
$ enstore://enstore/?volume=VOL001&location_cookie=0000_000000000_0000001&size=234653&file_family=standard&map_file=&
   pnfsid_file=0000464E839DEAFC428E8CF52D8028455141&pnfsid_map=&bfid=c085615502758c8bb54db4c30081626f&
   origdrive=localhost:/dev/tmp/tps0d0n:1487271284&crc=813392028&original_name=/pnfs/fs/usr/test/arossi/000/data001

### overwrite (cookie) [as root]

$ echo "enstore://enstore/?volume=VOL001&location_cookie=0000_000000000_0000002&size=234653&file_family=standard&
   map_file=&pnfsid_file=0000464E839DEAFC428E8CF52D8028455141&pnfsid_map=&bfid=c085615502758c8bb54db4c30081626f&
   origdrive=localhost:/dev/tmp/tps0d0n:1487271284&crc=813392028&original_name=/pnfs/fs/usr/test/arossi/000/data001"
   > ".(suri)(data001)"

$ cat ".(suri)(data001)"
$ enstore://enstore/?volume=VOL001&location_cookie=0000_000000000_0000002&size=234653&file_family=standard&map_file=&
   pnfsid_file=0000464E839DEAFC428E8CF52D8028455141&pnfsid_map=&bfid=c085615502758c8bb54db4c30081626f&
   origdrive=localhost:/dev/tmp/tps0d0n:1487271284&crc=813392028&original_name=/pnfs/fs/usr/test/arossi/000/data001

### append (cookie) [as root]

$ echo "enstore://enstore/?volume=VOL001&location_cookie=0000_000000000_0000003&size=234653&file_family=standard&
   map_file=&pnfsid_file=0000464E839DEAFC428E8CF52D8028455141&pnfsid_map=&bfid=c085615502758c8bb54db4c30081626f&
   origdrive=localhost:/dev/tmp/tps0d0n:1487271284&crc=813392028&original_name=/pnfs/fs/usr/test/arossi/000/data001"
   > ".(suri)(data001)"

$ cat ".(suri)(data001)"
$ enstore://enstore/?volume=VOL001&location_cookie=0000_000000000_0000002&size=234653&file_family=standard&map_file=&
   pnfsid_file=0000464E839DEAFC428E8CF52D8028455141&pnfsid_map=&bfid=c085615502758c8bb54db4c30081626f&
   origdrive=localhost:/dev/tmp/tps0d0n:1487271284&crc=813392028&original_name=/pnfs/fs/usr/test/arossi/000/data001,
   enstore://enstore/?volume=VOL001&location_cookie=0000_000000000_0000003&size=234653&file_family=standard&map_file=&
   pnfsid_file=0000464E839DEAFC428E8CF52D8028455141&pnfsid_map=&bfid=c085615502758c8bb54db4c30081626f&
   origdrive=localhost:/dev/tmp/tps0d0n:1487271284&crc=813392028&original_name=/pnfs/fs/usr/test/arossi/000/data001

### remove [as root]

$ echo -n "" > ".(suri)(data001)"

$ cat ".(suri)(data001)"
$
NOTES:

We record here a peculiar problem concerning permission error reporting using bash built-in ‘echo’.

Simple overwrite reports the error correctly:

$ echo -n "" > ".(suri)(data001)"
-bash: .(suri)(data001): Operation not permitted

Append, however, does not:

$ echo "[...]" >> ".(suri)(data001)"
$ echo $?
0
$ cat ".(suri)(data001)"
[shows the original location]

Note that the behavior is correct (the new location value has not been overwritten), but the return value for the process is 0, and no error is reported.

The executable [/usr]/bin/echo, however, works as it should:

$ /bin/echo  "[...]" >> ".(suri)(data001)"
/bin/echo: write error: Operation not permitted

This is also works properly in python.

A similar issue arises with errors involving invalid URIs: built-in echo does not report the error, but /bin/echo and python do.