Accessing Data

The automounter.
D0FS data.
FATMEN.
D0DAD virtual streams.
VMS project disks.
UNIX data disks.

The Automounter

The nfs mounting of all UNIX and VMS data and user disks that are accessible from the local UNIX machines is handled by a program called "automount" that runs as a daemon on each UNIX node. The automount configuration on the local UNIX nodes has the following features.

Automounted disks are mounted automatically when they are accessed.
Automounted disks that are not accessed for a period of time (typically five minutes) are automatically dismounted.
Automounted filesystems can be accessed from any node using the same pathname.
Automounted filesystems are invisible unless that are actually mounted.

These features imply that automounted disks are dismounted, and therefore invisible, most of the time. In order to access an antomounted filesystem, you need to know the exact pathname of that filesystem in advance. In some cases, the pathnames of automounted filesystems are stored in environment variables.

Accessing Data on D0FS

All of the D0FS data disks are nfs exported and are automounted on the local UNIX machines as explained above. The d0fs automount configuration file, containing a list of all automounted d0fs disks, can be viewed by typing the following command.

% ypcat -k auto.d0fs

All d0fs disks are accessed from the pathname /d0fs/disks.

When the D0 environment is initialiazed, several environment variables are defined to assist the user in locating various kinds of data on d0fs. Thus it is not necessary to know the names of individual d0fs disks. The most important d0fs environment variables are given below.

$d0fs_mc      Monte Carlo data (D0$DATA$MC).
$d0fs_stage   FATMEN staging area (DISK$STAGE).
$d0fs_d0dad   D0dad files (D0$DATA$D0DAD).
$d0fs_pick    Pick events data (D0$DATA$PICK).
$alpha_dst    DST data (D0$DATA$DST).
$alpha2_dst   DST data (D0$DATA$DST).

These environment variables are generally defined as search lists referring to several different disks. The DST environment variables are implemented as several different variables because of system imposed limits on the length of variable definitions.

VMS filename translation using standard D0 VMS logicals, such as D0$DATA$DST, is embedded in most D0 software, including d0open, the event i/o utilities, the program builder frameworks. There are also shell command line file finding utilities that accept VMS filenames.

Accessing Data via FATMEN

At present there is no FATMEN catalogue or software installed on D0 UNIX nodes. Nevertheless, D0FS data can be accessed via FATMEN name as described in d0$unix$docs:fatmen.doc. Translation and staging of FATMEN filenames into UNIX pathnames takes place from within d0open (d0$offline_util$general:d0open.for) by means of a remote execution of the FATMEN shell on a VMS node.

Accessing Data via D0DAD

D0dad access to virtually streamed data on D0FS is available from local D0 UNIX machines. To read data from a virtual stream, specify a "d0dad file" (file extension .d0dadf) to the D0 event utility (see d0$event_util:event_io_guide.doc). System-defined d0dad files can be found in $d0fs_d0dad (for omni_filter virtual streams) and $d0fs_d0dad/trigfilt (for level 1 trigger and level 2 filter virtual streams). Users can also define their own virtual streams. Refer to d0$d0dad$docs:users.ps for additional information.

VMS Project Disks

Currently, all VMS project disks (PRJ$ROOTxxx) are nfs exported from the FNALD0 and D0TNG clusters. A request has been made to nfs export the project disks from the D0SFT cluster, as well as the temp disks (TMP$ROOTxxx) from all three VMS clusters, but at the time of updating of this page, this has not yet been done (send complaints to helpdesk@fnalv).

Project disks are mounted under the path /prj_root. The automount configuration for the project disks can be viewed by typing the following command.

% ypcat -k auto.prj_root

Temp disks will be mounted under the path /tmp_root. The automount configuration for the temp disks can be viewed by typing the following command.

% ypcat -k auto.tmp_root

Environment variables for the project disks are not included in the default D0 environment. The command access can be used to define an environment variable for any given project disk. For example:

% access top_doc
top_doc: /prj_root/200/top_doc
% echo $top_doc
/prj_root/200/top_doc

Local UNIX Data Disks

Local data disks are automounted under a pathname that includes the server nodename, such as /d0sgi0/data1. A separate automount map exists for each local server. To view the automount configuration for a given server, for example d0sgi0, use the following command.

% ypcat -k auto.d0sgi0

At the present time, all space on the local data disks is owned by individuals. There is no group owned space, nor is there a formal mechanism for allocating space to specific projects.