PowerScale OneFS: How to Edit Crontab

Procedure

View the crontab files.

Run the appropriate command to view the cluster wide c (including additions from local node's specific) crontab file.

For cluster wide:

cat /etc/crontab

For just the local node crontab additional entries (that get added to /etc/crontab only on specific node):

cat /etc/local/crontab.local

OneFS generates the /etc/crontab file by combining the default template, /etc/mcp/override/crontab and /etc/local/crontab.local. A sample crontab entry is displayed below.

#minute hour    mday    month   wday    who     command
#
# Nightly Health check update

0       1       *       *       *       root    /usr/bin/isi_healthcheck_update -s

The following table explains the column headers:

This table explains the special characters:

Editing the crontab files.

Whenever possible, you should use a client and the API to effect scheduled jobs on the cluster. Directly adding crontab entries should be a last resort and must be verified to not cause disruption, instability or otherwise impact the cluster.

If there is a need for custom cronjobs, first discuss with your account team for creation of a feature request.

If the /etc/local/crontab.local file does not exist, use the command below to create:

touch /etc/local/crontab.local

Similarly, if the /etc/mcp/override/crontab file does not exist, use the command below to create:

touch /etc/mcp/override/crontab

cp /etc/local/crontab.local /etc/local/crontab.local.backup

An entry can be added directly by running the following command:

vi /etc/local/crontab.local

And similarly:

vi /etc/mcp/override/crontab

Paste or type the required entry as shown in the below example:

To add treedelete.sh to run at 11 PM daily:

0     23     *     *     *     root     /bin/sh     /ifs/data/Scripts/treedelete.sh

Using isi_ropc in crontab entries

Adding isi_ropc to a crontab entry runs the passed command at most once per cluster per version no matter how many nodes it is run on. Without a flag, this would allow the command to run on the node with the lowest DevID. Alternatively, adding the -s flag would run the command on a random node. An example entry is below:

# rotate log files on /ifs, too -- one node per cluster at a time

15,45   *       *       *       *       root    isi_ropc newsyslog -f /etc/newsyslog.ifs.conf

Add multiple entries to a crontab file.

If a crontab file requires multiple entries from another file, append the job entry. This example where path_to_file_with_entries is the file that contains the entries to be imported:

cat /ifs/<path_to_file_with_entries> >> /etc/local/crontab.local

Verify entries are propageted correctly to the system's crontab file.

Output similar to the following is displayed at the bottom of the output:

tail -n 50 /etc/crontab

# X: ----------------
# X: OVERRIDE
# X: This section contains user changes which will be
# X: preserved between product versions. It is
# X: populated from the contents of the file
# X: /etc/mcp/override/crontab
# X: ----------------


# X: ----------------
# X: LOCAL
# X: This section contains entries local to this node
# X: only. This section is populated from the contents of
# X: the file /etc/local/crontab.local if it exists.
# X: ----------------
0 23 * * * root /bin/sh /ifs/data/Scripts/treedelete.sh

Revert changes to the crontab file:

These steps revert the crontab.local file to the backup version that were created in the previous section.

1. Open an SSH connection on any node in the cluster and log in using the root account.
2. Run the following command to copy and then rename the original backup of the crontab.local file:

cp /etc/local/crontab.local.backup /etc/local/crontab.local

Prior to OneFS 9.5, /etc/mcp/override/crontab.smbtime was used to preserve entries through upgrades. It has since been determined that beginning with OneFS 9.5 and later, use /etc/mcp/override/crontab instead of /etc/mcp/override/crontab.smbtime.