Re: btrfs hang on nfs?

["Scott E. Blomquist" <sb@techsquare.com>]

Jojo writes:
 > 
 > Within scheduler there were some changes according to device queueing.
 > Kernels after 4.16 and before 4.19.8 were problematic, as we recognized
 > here.
 > This seemed to be a regression on the "kyber" scheduler, as recognized here:
 > [root@pc7 sysctl.d]# cat /sys/block/sdc/queue/scheduler
 > mq-deadline [kyber] bfq none
 > 
 > As work around you may change the disc scheduler to an "old" one, like
 > 
 > Test it like this for all of your devices:
 > root@pc7:~/ # echo bfq > /sys/block/sdX/queue/scheduler
 > 
 > For permanent add a file config to your /etc/sysctl.d.
 > EXAMPLE, edit it to your requirements.
 > 
 > [root@pc7 sysctl.d]# cat /etc/sysctl.d/90-sysscheduler.conf
 > #disk scheduler
 > block.sda.queue.scheduler = md-deadline
 > block.sdb.queue.scheduler = md-deadline
 > block.sdg.queue.scheduler = bfq
 > block.sdh.queue.scheduler = bfq
 > block.sdi.queue.scheduler = bfq
 > 
 > 
 > Hope this may help you.
 > It did work for me here.
 > 
 > Better Idea is to upgrade the kernel to 4.19.13 (which is a LTS Kernel)
 > 
 > mit freundlichen Gr  en
 > J rgen Sauer

Thank you so much, I would have never guessed that.

In my case the scheduler was set to deadline

    cat /sys/block/sd[a-c]/queue/scheduler
    noop [deadline] cfq
    noop [deadline] cfq
    noop [deadline] cfq

I have set it to cfq, I did not see an option for bfq.

I am also building 4.19.13 and will swap that in ASAP.

Thanks again,

Cheers,

sb. Scott Blomquist