On 07.11.19 15:55, van Sleeuwen, Berry wrote:
> Hi All,
>
> I have installed an Ubuntu 19-04 but as it turns out the application requires
> version 18-04. So I have installed a new 18-04 system.
>
> Next I tried to move the LVM from the 19-04 machine into the 18-04 machine.
> But I can’t get the disks online. The first few disks are fine but at a
> certain point the server crashes. During “chccwdev -e” at some point all
> memory is exhausted and I see a lot of CPU and IO. Eventually the OOM-killer
> kicks in to kill various processes. The server is no longer responding and
> only a reboot (force and xautolog) will get the server back online.
>
> Next I have added a new range of disks instead of reusing the old.
> Unfortunately with the empty disks I got into the same situation. But
> eventually, after formatting the disks one-by-one, I was able to get a new
> filesystem available. Even during reboot the new filesystem is activated
> without a problem. So it looks like for some reason the problem went away.
> But when I add another filesystem the machine once again crashes during
> activation of the disks.
>
> What could cause this to happen? I am reluctant to hand over this machine as
> we might get into the same problem when we need to add additional disks.
Hi Berry,
what exact kernel version are we talking about? Unfortunately after
start using blk-mq the DASD driver used a lot of memory for a single
device due to a quite optimistic number of hardware queues and queue
depth. This was significantly improved with
commit 3284da34a87a ("s390/dasd: reduce the default queue depth and nr
of hardware queues")
which is available since kernel 4.18. This is should be available in
Ubuntu 18.04.2 as far as I know.
So if you are using 18.04(.1) with kernel 4.15 this might be a problem
and I would suggest to upgrade to 18.04.2 with kernel 4.18 or later.
Regards,
Stefan
>
> Met vriendelijke groet/With kind regards/Mit freundlichen Grüßen,
> Berry van Sleeuwen
> Flight Forum 3000 5657 EW Eindhoven
> • +31 (0)6 22564276
> [cid:[email protected]]
> [cid:[email protected]]
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