Add PID of the cta-taped processes to the output of cta-admin --json dr ls

With tape servers connected to multiple drives, we need to be able to easily distinguish which process is using which drive:

[vlado@tpsrv520 /]$ pstree -p | grep cta | grep master
           |-cta-tpd-master(2667)-+-cta-tpd-IBMLIB1(2532606)-+-{cta-tpd-IBMLIB1}(2532607)
           |-cta-tpd-master(2043843)-+-cta-tpd-IBMLIB1(2532706)-+-{cta-tpd-IBMLIB1}(2532707)

Currently, the --json output of cta-admin dr ls does not contain PIDs.

[vlado@tpsrv520 /]$ cta-admin --json dr ls IBMLIB1-LTO9-F06C3R3 | jq . | grep -i pid
[vlado@tpsrv520 /]$ cta-admin --json dr ls IBMLIB1-LTO9-F06C3R3 | jq . | grep -i 2532606
[vlado@tpsrv520 /]$ cta-admin --json dr ls IBMLIB1-LTO9-F06C3R3 | jq . | grep -i 2532706

Please add it, in particular the PIDs of the processes serving the drives and doing the transfers.

added Needs Discussion Tape server labels

changed title from Add PID of the cta-taped processes to the output of cta-admin dr ls to Add PID of the cta-taped processes to the output of cta-admin --json dr ls

changed the description

This probably requires a new column in the DRIVE_CONFIG table:

• https://gitlab.cern.ch/cta/cta-catalogue-schema/-/blob/main/common_catalogue_schema.sql?ref_type=heads#L421-L428

It would need to be updated every time a new DriveHandler subprocess is created.

Some time ago I did a change to the thread naming to improve the situation, from the next release the name of the drive thread will be something like: cta-tpd-F06C3R; depending on the drive name length last characters might be trimmed. The limitation here is the 15 character limit for thread names. We could also remove the cta-tpd-, to have extra information about the drive name

6c0acc16

Pablo, having PID in the --json output is really needed for other use cases as well.

Regarding the names of the daemons, how about:

• cta-tpd-master - for the mother forker
• cta-tpd-maint - for the maintenance process
• cta-tpd-drv-X - for the drive process where X = number in the device name /dev/nstX?

For now as a workaround for operators:

# List processes from cta user
[root@tpsrv608 ~]# ps -u cta
    PID TTY          TIME CMD
1286417 ?        00:01:18 cta-tpd-master
1286648 ?        00:00:05 cta-rmcd
2419294 ?        13:26:30 cta-tpd-maint
3781164 ?        03:56:48 cta-tpd-SPECTRA

# Looks its arguments: drive name is there: SPECTRALIB2-LTO9-F10B3S2
[root@tpsrv608 ~]# cat /proc/3781164/cmdline 
/usr/bin/cta-taped--log-format=json--log-to-file=/var/log/cta/cta-taped-SPECTRALIB2-LTO9-F10B3S2.log--config=/etc/cta/cta-taped-SPECTRALIB2-LTO9-F10B3S2.conf

assigned to @afonso

As discussed in the dev meeting, we will preserve this piece of information (PID) as a new column in the CTA Catalogue.

added File catalogue priorityhigh labels

added 1 deleted label

removed Needs Discussion label

@vlado , this is the shortcut that I mentioned.

Let me know if this works. It would be nice being able to avoid adding this extra column to the catalogue:

[root@tpsrv521 cta]# ps -eo pid,comm,args | grep cta-tpd | grep IBMLIB1-LTO9-F06C4R1
   2646 cta-tpd-master  /usr/bin/cta-taped --log-format=json --log-to-file=/var/log/cta/cta-taped-IBMLIB1-LTO9-F06C4R1.log --config=/etc/cta/cta-taped-IBMLIB1-LTO9-F06C4R1.conf
 608837 cta-tpd-maint   /usr/bin/cta-taped --log-format=json --log-to-file=/var/log/cta/cta-taped-IBMLIB1-LTO9-F06C4R1.log --config=/etc/cta/cta-taped-IBMLIB1-LTO9-F06C4R1.conf
2167452 cta-tpd-IBMLIB1 /usr/bin/cta-taped --log-format=json --log-to-file=/var/log/cta/cta-taped-IBMLIB1-LTO9-F06C4R1.log --config=/etc/cta/cta-taped-IBMLIB1-LTO9-F06C4R1.conf

With the change mentioned by @poliverc in #778 (comment 8217402) this command probably can be further simplified.

As discussed with @vlado , this workaround can be used in the cta-ops-admin dr ls --local command. To be implemented by @idlarbi .

Therefore, we can close this ticket.

Ii have created the following issue on CTA operations to cover this: https://gitlab.cern.ch/cta/operations/-/issues/1497

closed