[mythtv-users] monthly madam checkarray kills recordings

scram69 scram69 at gmail.com
Sun May 6 16:27:08 UTC 2018


It's the first Sunday of the month, so I've just gone through the first
raid checkarray re-sync on Ubuntu 18.04, having just upgraded from 14.04.
 /etc/cron.d/mdadm runs checkarray with the --idle argument, presumably so
as not to kill disk performance for other processes.

However, during the array check, all recordings failed with
threadedfilewriter errors:

May  6 05:00:55 mediaserver mythbackend: mythbackend[1960]: E
HDHRStreamHandler threadedfilewriter.cpp:239 (Write)
TFW(/var/lib/mythtv/recordings/2071_20180506120000.ts:61): Maximum buffer
size exceeded.#012#011#011#011file will be truncated, no further writing
will be done.#012#011#011#011This generally indicates your disk performance
#012#011#011#011is insufficient to deal with the number of on-going
#012#011#011#011recordings, or you have a disk failure.
May  6 05:00:55 mediaserver mythbackend: mythbackend[1960]: I
HDHRStreamHandler recorders/dtvrecorder.cpp:350 (BufferedWrite) DTVRec[13]:
BufferedWrite: Writes are failing, setting status to Failing

indicating that the array performance is suffering due to checkarray.

Apparently, this has been a problem since 16.04, from this blog post:
https://fhackts.wordpress.com/2017/11/10/software-raid-check-killing-ubuntu-16-04-servers/
but I can't find any other instances of people running into it, nor any
solutions.

Needless to say, Sunday morning cron checkarrays ran harmlessly and posed
no problem to recordings under mythbuntu 14.04.  Has anyone else seen this
and been able to fix it?



-- 
________________________
"destroying the fundamental underpinnings of the broadcast television
ecosystem"
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