Ok, here we have the corresponding LP bug: https://bugs.launchpad.net/ubuntu-z-systems/+bug/1852257 (you are welcome to click on "This bug affects 1 person. Does this bug affect you?" -- between title and Status on the top ...)
On Tue, Nov 12, 2019 at 3:19 PM van Sleeuwen, Berry < [email protected]> wrote: > We are running with the 4.18 kernel so the issue itself is solved. If > anything, we might go to version 5.0, I don't think we want to go back to > 4.15. > > But as for large disk sets, if it wasn't for our indexing service we could > run our Samba machine in 400MB. That includes an LVM with 40 disks (model > 9). Apart from a few K for each disk I wouldn't expect the size of the > machine to be so dependent of the number of disks. I would expect the > memory size of a system depends on the application instead of the amount of > (potential) storage in a filesystem. > > We have a TSM server that has 72 disks (model 54). We have 2G assigned to > the machine, but I think it could even run happily in 1G (or maybe even > less). > > Met vriendelijke groet/With kind regards/Mit freundlichen Grüßen, > Berry van Sleeuwen > Flight Forum 3000 5657 EW Eindhoven > > -----Original Message----- > From: Linux on 390 Port <[email protected]> On Behalf Of Frank > Heimes > Sent: Tuesday, November 12, 2019 2:45 PM > To: [email protected] > Subject: Re: Ubuntu 18-04 unable to add DASD > > Hi Berry, > thanks for the add. background info. > I just wondered, because small system are okay (and still often used on > s390x) - and our minimum is - as of today- 512MB (even if we recommend > 1GB +). > When I came across installations with several 'smaller' systems, they had > usually very few resources overall (incl. disks - mostly just one or a > handful, due to partial filesystem sharing). > > In your case a smaller system is used in combination with a larger set of > disks - hence my question. > But looks like you're preparing biggers systems with the help of a smaller > one - I see. > > I'm glad that you can keep going with your (bigger) 32GB system - or > alternatively with using the HWE kernel. > > I'll keep you posted on the kernel 4.15 update ... > > Bye, Frank > > > On Tue, Nov 12, 2019 at 2:17 PM van Sleeuwen, Berry < > [email protected]> wrote: > > > Hi Frank, > > > > I started with an installation in 900M. For the installation itself > > it's good enough but when additional disks were activated I ran into > problems. > > Later I tried in 2G with the same problem. Only when I moved to the > > target guest (32G) I could successfully enable the application disks. > > And then I could really see the cause of the problem. When I activated > > disks the memory usage reported in top was 2.6GB. And I guess, since > > it's hardware related memory, it is not eligible for swap so the > > system tries to swap other processes and eventually the oom kills even > the critical processes. > > > > Indeed 20 disks might just kept you out of problems but probably you > > were already close to the edge. > > > > Depending on the purpose of the server, we have a lot of small servers. > > (In the past even as low as 130MB.) We have found that for a Suse > > zypper update we minimally require about 400MB so that's our baseline > > for some servers. But even an active Samba machine only has 900M, > > mostly because of an indexer process that requires quite some memory. > > Our case for Ubuntu is Machine Learning and this server is currently > > defined with 32GB, so I could quite easy go into that server to see > > what was going on after the base installation. > > > > Met vriendelijke groet/With kind regards/Mit freundlichen Grüßen, > > Berry van Sleeuwen Flight Forum 3000 5657 EW Eindhoven > > > > -----Original Message----- > > From: Linux on 390 Port <[email protected]> On Behalf Of Frank > > Heimes > > Sent: Tuesday, November 12, 2019 12:22 PM > > To: [email protected] > > Subject: Re: Ubuntu 18-04 unable to add DASD > > > > Hi, > > I just completed some rough tests on a pretty small LPAR (just 1.,5GB > > RAM) and I ran the GA kernel 4.15 as well as the HWE kernel 5.0. > > > > An activation of another DASD device requires on kernel 5.0 about 90% > > less memory compared to kernel 4.15 - so there is indeed a big > difference. > > However, with the 20 DASDs that I had left for the test I wasn't able > > to run in an OOM situation, but the memory left decreased consistently... > > > > Berry, may I ask how big the system is that you are using (regading RAM)? > > > > Bye, Frank > > > > > > This e-mail and the documents attached are confidential and intended > > solely for the addressee; it may also be privileged. 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