rear backup process takes too long with many disks
Environment
- Red Hat Enterprise Linux (RHEL) 6,7
- rear-1.17.2
- rear-2.00
- rear-2.4.2
Issue
When a system has many multipath devices (~500 disks and paths), creating the ReaR rescue takes several hours.
Resolution
- For RHEL 6 update to
rear-1.17.2-8.el6_10shipped with Advisory RHBA-2019:2475 or newer. - For RHEL 7 update to
rear-2.4-7.el7shipped with Advisory RHBA-2019:2273 or newer.
Root Cause
Previously, ReaR employed several time consuming or redundant calls:
- the
get_device_name()function to scan all multipath devices multiple times without caching the information (legacy code, when kernel has no/sys/block/<dev>/dm/namenode) - the
get_device_name()function to scan the multipath devices even if the results were not used - the collect of unused
/sys/class/fc_transportinformation
After optimizations implemented, the ReaR rescue takes several minutes only.
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