Hi Ray, Once the guest touches a page in the VDISK, VM will allocate that page and keep it forever until the VDISK is destroyed. So, simply telling the guest to turn off/on the swap will not tell somehow magically release those pages. The only way I know to actually release these pages from the VM storage is to set swap off, then detach the VDISK virtual address from the guest (first setting it offline I guess), then redefine a new virtual disk, format it within the guest (since you can't do SWAPGEN on it at this point), then set the swap on. This all assumes that the guest is allowed to define its own VDISK.
Aria -----Original Message----- From: Linux on 390 Port [mailto:LINUX-390@VM.MARIST.EDU] On Behalf Of Mrohs, Ray (JMD) Sent: Wednesday, December 09, 2015 3:05 PM To: LINUX-390@VM.MARIST.EDU Subject: Status of VDISK after swap space usage Hi, Our environment consists of SLES 11.4 servers under VM 6.2. Sometimes we have misbehaving Linux applications that dip heavily into the SWAPGEN configured swap space. After things settle down, Linux never lets go of the space until we issue a swapoff -a, and swapon -a. Of course I do this after making sure that we have sufficient free memory available in that server. The reported swap use then effectively returns to zero. But it seems like nobody tells VM because the VDISK being retained in memory for that virtual machine, as reported by Velocity, is consistent with the maximum swap space that was used, something on the order of 190K pages, and it never decreases even though the Linux swap use stays at zero. Does VM ignore this until it hits a memory use threshold, or does Linux not clean up well after itself, or maybe we are missing something else? We are trying to avoid a "just reboot it" action. This is our typical swap disk entry in fstab: /dev/disk/by-path/ccw-0.0.0105 swap swap defaults 0 0 Ray Mrohs Lockheed Martin Corporation Service Delivery Staff Infrastructure Operations ray.mr...@usdoj.gov 202 307-6896 ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 ---------------------------------------------------------------------- For more information on Linux on System z, visit http://wiki.linuxvm.org/ ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 ---------------------------------------------------------------------- For more information on Linux on System z, visit http://wiki.linuxvm.org/
