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. If you receive this > e-mail in error, please notify the sender immediately and destroy it. As > its integrity cannot be secured on the Internet, Atos’ liability cannot be > triggered for the message content. Although the sender endeavours to > maintain a computer virus-free network, the sender does not warrant that > this transmission is virus-free and will not be liable for any damages > resulting from any virus transmitted. On all offers and agreements under > which Atos Nederland B.V. supplies goods and/or services of whatever > nature, the Terms of Delivery from Atos Nederland B.V. exclusively apply. > The Terms of Delivery shall be promptly submitted to you on your request. > > ---------------------------------------------------------------------- > For LINUX-390 subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO LINUX-390 or > visit > http://www2.marist.edu/htbin/wlvindex?LINUX-390 > ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO LINUX-390 or visit http://www2.marist.edu/htbin/wlvindex?LINUX-390
