Data Domain File System - PANIC: ddr/repl/lrepl_client.c: lrepl_srepl_recipe_get_next: 1972: !(*target_off >= region_start_off)

Summary: This KB article explains the reason and the workaround for a condition while recipe replication is taking place on DDOS 6.x versions, which results in a Data Domain file system crash.

This article applies to This article does not apply to This article is not tied to any specific product. Not all product versions are identified in this article.
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Symptoms

A Data Domain file system running DDOS 6.x code and acting as the source for replication may experience multiple PANICs when the recipe replication feature is enabled, with the Data Domain logging error messages such as below: 
ERROR: MSG-INTRNL-00001: PANIC: ddr/repl/lrepl_client.c: lrepl_srepl_recipe_get_next: 1972: !(*target_off >= region_start_off)

Most times the FS process tries to start following the PANIC, but fails shortly after coming up. This is particularly so when using directory or MTree replication, instead of BOOST MFR. As soon as the same file being replicated is attempted to be replicated again to destination, the FS may give up trying and be disabled.

Cause

Due to a code defect, the Data Domain File System PANICs, dumps core and restarts when recipe replication enabled.
In earlier DDOS releases it is not deleting all chucks when the basefile for a given backup being replicated out has been removed or overwritten.
A "basefile" is any pre-existing backup file that a later backup may use as a reference for the backups to be synthesized.
Older versions in the DDOS 6.0.x , 6.1.x and 6.2.x are affected by this defect.

Resolution

If checking this KB article you have most likely already hit the defect and probably have the FS down, so even if this defect is fixed in later DDOS releases (see below) you must first apply the workaround, consisting of either disabling replication altogether, or disabling the recipe replication feature:
  • To disable replication, run "replication disable all", and try to bring the FS up by running "filesys enable"
  • To disable recipe replication only:
    • Log in the DD as "sysadmin" or equivalent user, and turn to "SE mode"
    • NOTE: SE commands have been deprecated in DDOS versions 7.7.5.25, 7.10.1.15, 7.13.0.15, 6.2.1.110 and above and are accessible only by Dell employees
    • If the FS is not disabled yet, do it now (filesys disable)
    • Change the default setting for recipe replication, so that using recipe replication when replicating out backups is disabled: se sysparam set RECIPE_REPL_ENABLED=FALSE
    • You can now enable the FS (filesys enable) and replication, if it was disabled earlier (replication enable all)
It is recommended to disable recipe replication only on the source rather than disabling replication entirely. Disabling all replication grows the replication lag.
The side effects of disabling recipe replication only are limited to some minor performance reduction when replicating backups.

The code defect causing this issue has been fixed in the following releases:
  • DDOS 6.1.2.40 and later
  • DDOS 6.2.0.30 and later
  • DDOS 7.0.x will have this corrected on initial release
Note however the defect also affects DDOS 6.0.x releases, but there is no DDOS 6.0.x release with this defect fixed yet.

Affected Products

Data Domain

Products

Data Domain, DD OS 6.2, DD OS 6.0, DD OS 6.1
Article Properties
Article Number: 000056026
Article Type: Solution
Last Modified: 11 Dec 2023
Version:  3
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