Data Domain: Intermittent panics when ingesting data using NFSv4 with the default NFS options.

The DD FS process may experience intermittent PANICs, dump core and restart, when ingesting data using NFSv4 with the default NFS options, if running earlier DDOS 6.1.x releases, with PANIC strings such as the following:

ERROR: MSG-INTRNL-00001: PANIC: ddr/nfs4/nfs4_idmap/nfs4_names.c: _perform_timed_lookup: 698: !(active_cookie->magic == NFS4_IDMAP_LOOKUP_ARG_USED).

The defect has been fixed in the code for the following DDOS releases:

• DDOS 6.1.1.1 and later
• DDOS 6.1.2.0 and later

If a customer can't immediately upgrade to or the releases are not available, there is a possible workaround to try, however it will be necessary first to confirm the issue being the one described here:

• Are any non-root users used to perform I/O on the NFSv4 mount on clients?
• Is NFSv4 ID mapping on the client is enabled? On Linux, run "cat /sys/module/nfs/parameters/nfs4_disable_idmapping" to find out.
• Is the NFS client using Kerberos security (sec=krb5) for any NFSv4 export?
• Are there NFSv4 ACLs being used?

If the answer to all the above questions is 'NO', then an immediate workaround is to disable NFSv4 ID mapping on the DDR by running the following from the DD CLI:

# nfs option set nfs4-idmap-out-numeric always

This will ensure that the code path that caused the PANIC will not be hit, and will cause no issues with normal backups due to them not using any of the features in the "prechecks" mentioned above.

After upgrading to a fixed release, this setting should be reset:

# nfs option reset nfs4-idmap-out-numeric