Date: Mon, 3 Feb 2020 09:53:44 +0100 From: Andrea Venturoli <ml@netfence.it> To: freebsd-questions@freebsd.org Subject: mksnap_ffs regression? Message-ID: <ad74ef6c-d10a-c05c-88ee-42402670ebd5@netfence.it>
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Hello. On several servers I manage, I take backups to an external HD and use mksnap_ffs to create snapshots. I've never had troubles with this up to 11.3. Lately I started doing this on a 12.1 server and noticed mksnap_ffs will hang the box for several minutes (services stuck, no login allowed, already established ssh sessions partially work; shutdown not feasible unless reset button is pressed). N.B. This is an external drive, only mounted when needed and only accessed to make backups, so if *it* got stuck, it should not affect the whole system. I decided to check this and took the external HD to my desktop (11.3): it worked perfectly. I then upgraded my desktop to 12.1p2 and it started doing as above: _ mksnap_ffs will work for several minutes under high I/O (the HD is 6TB); meanwhile, the system is responsive; _ then mksnap_ffs will drastically reduce its I/O (at least as measured with top), but will keep working for some other minutes: during this phase, I cannot open any new program; ThunderBird gets stuck, while FireFox still works (but cannot open any new window); audacity keeps playing the current truck, but will get stuck on moving to the next; already open terminal windows might partially work; _ then mksnap_ffs will exit and everything will get back to normal. This is of course unacceptable on a production system. Is there any known problem with mksnap_ffs on 12.1? Any tweak/patch I should try? bye & Thanks av.
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