------- Comment From swgre...@us.ibm.com 2017-10-17 18:34 EDT------- Hi folks.
Good news! We got a test window on the Ubuntu KVM host today. We provisioned a collection of 24 new virtual Ubuntu guests for this test. Each virtual domain uses a single qcow2 virtual boot volume. All guests are configured exactly the same (except guests zs93kag100080, zs93kag100081 and zs93kag100082 are on a macvtap interface. Otherwise, identical.). Here's a sample of one (running) guest's XML: ubuntu@zm93k8:/home/scottg$ virsh dumpxml zs93kag100080 <domain type='kvm' id='65'> <name>zs93kag100080</name> <uuid>6bd4ebad-414b-4e1e-9995-7d061331ec01</uuid> <memory unit='KiB'>4194304</memory> <currentMemory unit='KiB'>4194304</currentMemory> <vcpu placement='static'>2</vcpu> <resource> <partition>/machine</partition> </resource> <os> <type arch='s390x' machine='s390-ccw-virtio-xenial'>hvm</type> </os> <clock offset='utc'/> <on_poweroff>destroy</on_poweroff> <on_reboot>restart</on_reboot> <on_crash>preserve</on_crash> <devices> <emulator>/usr/bin/qemu-kvm</emulator> <disk type='file' device='disk'> <driver name='qemu' type='qcow2' cache='none' io='native'/> <source file='/guestimages/data1/zs93kag100080.qcow2'/> <backingStore type='file' index='1'> <format type='raw'/> <source file='/rawimages/ubu1604qcow2/ubuntu.1604-1.20161206.v1.raw.backing'/> <backingStore/> </backingStore> <target dev='vda' bus='virtio'/> <boot order='1'/> <alias name='virtio-disk0'/> <address type='ccw' cssid='0xfe' ssid='0x0' devno='0x0000'/> </disk> <disk type='file' device='disk'> <driver name='qemu' type='raw' cache='none' io='native'/> <source file='/guestimages/data1/zs93kag100080.prm'/> <backingStore/> <target dev='vdc' bus='virtio'/> <alias name='virtio-disk2'/> <address type='ccw' cssid='0xfe' ssid='0x0' devno='0x0006'/> </disk> <disk type='file' device='cdrom'> <driver name='qemu' type='raw'/> <backingStore/> <target dev='sda' bus='scsi'/> <readonly/> <alias name='scsi0-0-0-0'/> <address type='drive' controller='0' bus='0' target='0' unit='0'/> </disk> <controller type='usb' index='0' model='none'> <alias name='usb'/> </controller> <controller type='scsi' index='0' model='virtio-scsi'> <alias name='scsi0'/> <address type='ccw' cssid='0xfe' ssid='0x0' devno='0x0002'/> </controller> <interface type='bridge'> <mac address='02:00:00:00:40:80'/> <source bridge='ovsbridge1'/> <vlan> <tag id='1297'/> </vlan> <virtualport type='openvswitch'> <parameters interfaceid='cd58c548-0b1f-47e7-9ed5-ad4a1bc8b8e0'/> </virtualport> <target dev='vnet0'/> <model type='virtio'/> <alias name='net0'/> <address type='ccw' cssid='0xfe' ssid='0x0' devno='0x0001'/> </interface> <console type='pty' tty='/dev/pts/3'> <source path='/dev/pts/3'/> <target type='sclp' port='0'/> <alias name='console0'/> </console> <memballoon model='none'> <alias name='balloon0'/> </memballoon> </devices> <seclabel type='dynamic' model='apparmor' relabel='yes'> <label>libvirt-6bd4ebad-414b-4e1e-9995-7d061331ec01</label> <imagelabel>libvirt-6bd4ebad-414b-4e1e-9995-7d061331ec01</imagelabel> </seclabel> </domain> To set up the test, we shutdown all virtual domains, and then ran a script which simply starts the guests, one at a time and captures fs .aio-nr before / after each 'virsh start'. After attempting to start all guests in the list, it goes into a loop, checking fs.aio-nr once every minute for 10 minutes to see if that value changes (which it does not). ubuntu@zm93k8:/home/scottg$ ./start_macvtaps_debug.sh Test started at Tue Oct 17 17:48:29 EDT 2017 cat /proc/sys/fs/aio-max-nr 65535 fs.aio-nr = 0 Starting zs93kag100080 ; Count = 1 zs93kag100080 started succesfully ... fs.aio-nr = 6144 Starting zs93kag100081 ; Count = 2 zs93kag100081 started succesfully ... fs.aio-nr = 12288 Starting zs93kag100082 ; Count = 3 zs93kag100082 started succesfully ... fs.aio-nr = 18432 Starting zs93kag100083 ; Count = 4 zs93kag100083 started succesfully ... fs.aio-nr = 24576 Starting zs93kag100084 ; Count = 5 zs93kag100084 started succesfully ... fs.aio-nr = 30720 Starting zs93kag100085 ; Count = 6 zs93kag100085 started succesfully ... fs.aio-nr = 36864 Starting zs93kag70024 ; Count = 7 zs93kag70024 started succesfully ... fs.aio-nr = 43008 Starting zs93kag70025 ; Count = 8 zs93kag70025 started succesfully ... fs.aio-nr = 49152 Starting zs93kag70026 ; Count = 9 zs93kag70026 started succesfully ... fs.aio-nr = 55296 Starting zs93kag70027 ; Count = 10 zs93kag70027 started succesfully ... fs.aio-nr = 61440 Starting zs93kag70038 ; Count = 11 zs93kag70038 started succesfully ... fs.aio-nr = 67584 Starting zs93kag70039 ; Count = 12 zs93kag70039 started succesfully ... fs.aio-nr = 73728 Starting zs93kag70040 ; Count = 13 zs93kag70040 started succesfully ... fs.aio-nr = 79872 Starting zs93kag70043 ; Count = 14 zs93kag70043 started succesfully ... fs.aio-nr = 86016 Starting zs93kag70045 ; Count = 15 zs93kag70045 started succesfully ... fs.aio-nr = 92160 Starting zs93kag70046 ; Count = 16 zs93kag70046 started succesfully ... fs.aio-nr = 98304 Starting zs93kag70047 ; Count = 17 zs93kag70047 started succesfully ... fs.aio-nr = 104448 Starting zs93kag70048 ; Count = 18 zs93kag70048 started succesfully ... fs.aio-nr = 110592 Starting zs93kag70049 ; Count = 19 zs93kag70049 started succesfully ... fs.aio-nr = 116736 Starting zs93kag70050 ; Count = 20 zs93kag70050 started succesfully ... fs.aio-nr = 122880 Starting zs93kag70051 ; Count = 21 zs93kag70051 started succesfully ... fs.aio-nr = 129024 Starting zs93kag70052 ; Count = 22 Error starting guest zs93kag70052 . error: Failed to start domain zs93kag70052 error: internal error: process exited while connecting to monitor: 2017-10-17T21:49:06.684444Z qemu-kvm: -drive file=/guestimages/data1/zs93kag70052.qcow2,format=qcow2,if=none,id=drive-virtio-disk0,cache=none,aio=native: Could not refresh total sector count: Bad file descriptor fs.aio-nr = 129024 Starting zs93kag70053 ; Count = 23 Error starting guest zs93kag70053 . error: Failed to start domain zs93kag70053 error: internal error: process exited while connecting to monitor: 2017-10-17T21:49:07.933457Z qemu-kvm: -drive file=/guestimages/data1/zs93kag70053.qcow2,format=qcow2,if=none,id=drive-virtio-disk0,cache=none,aio=native: Could not refresh total sector count: Bad file descriptor fs.aio-nr = 129024 Starting zs93kag70054 ; Count = 24 Error starting guest zs93kag70054 . error: Failed to start domain zs93kag70054 error: internal error: process exited while connecting to monitor: 2017-10-17T21:49:09.084863Z qemu-kvm: -drive file=/guestimages/data1/zs93kag70054.qcow2,format=qcow2,if=none,id=drive-virtio-disk0,cache=none,aio=native: Could not refresh total sector count: Bad file descriptor fs.aio-nr = 129024 Monitor fs.aio-nr for 10 minutes, capture value every 60 seconds... Sleeping 60 seconds. Loop count = 1 fs.aio-nr = 129024 Sleeping 60 seconds. Loop count = 2 fs.aio-nr = 129024 Sleeping 60 seconds. Loop count = 3 fs.aio-nr = 129024 Sleeping 60 seconds. Loop count = 4 fs.aio-nr = 129024 Sleeping 60 seconds. Loop count = 5 fs.aio-nr = 129024 Sleeping 60 seconds. Loop count = 6 fs.aio-nr = 129024 Sleeping 60 seconds. Loop count = 7 fs.aio-nr = 129024 Sleeping 60 seconds. Loop count = 8 fs.aio-nr = 129024 Sleeping 60 seconds. Loop count = 9 fs.aio-nr = 129024 Sleeping 60 seconds. Loop count = 10 fs.aio-nr = 129024 Test completed successfully. ## I couldn't understand why the error messages on start up were different this time, ## however it seems to be the same underlying cause. That is, if I stop one domain, I am ## then able to successfully start a failed domain. For example, ubuntu@zm93k8:/home/scottg$ virsh start zs93kag70052 Domain zs93kag70052 started ubuntu@zm93k8:/home/scottg$ virsh list |grep zs93kag70052 89 zs93kag70052 running ubuntu@zm93k8:/home/scottg$ ## And now, if I try to start zs93kag70051 (which started fine the first time), it fails (with yet a different error): ubuntu@zm93k8:/home/scottg$ virsh start zs93kag70051 error: Disconnected from qemu:///system due to I/O error error: Failed to start domain zs93kag70051 error: End of file while reading data: Input/output error error: One or more references were leaked after disconnect from the hypervisor ubuntu@zm93k8:/home/scottg$ ubuntu@zm93k8:/home/scottg$ date;sysctl fs.aio-nr Tue Oct 17 18:16:18 EDT 2017 fs.aio-nr = 129024 ## This time, I will kill one of the ovs-osa networked guests, and see if that then allows me to start zs93kag70051 ... (it does) ubuntu@zm93k8:/home/scottg$ date;virsh destroy zs93kag100080 Tue Oct 17 18:18:29 EDT 2017 Domain zs93kag100080 destroyed ubuntu@zm93k8:/home/scottg$ sysctl fs.aio-nr Tue Oct 17 18:19:18 EDT 2017 fs.aio-nr = 122880 ubuntu@zm93k8:/home/scottg$ date;virsh start zs93kag70051 Tue Oct 17 18:18:41 EDT 2017 Domain zs93kag70051 started ubuntu@zm93k8:/home/scottg$ date;sysctl fs.aio-nr Tue Oct 17 18:18:52 EDT 2017 fs.aio-nr = 129024 ## It appears that fs.aio-nr = 129024 is "The Brick Wall". ## Now, let's try increasing fs.aio-max-nr to 4194304 and see if that allows me to start more guests (it does). ubuntu@zm93k8:/home/scottg$ sudo sysctl -p /etc/sysctl.conf fs.aio-max-nr = 4194304 ubuntu@zm93k8:/home/scottg$ cat /proc/sys/fs/aio-max-nr 4194304 ubuntu@zm93k8:/home/scottg$ date;virsh start zs93kag70051 Tue Oct 17 18:27:54 EDT 2017 Domain zs93kag70051 started ubuntu@zm93k8:/home/scottg$ date;sysctl fs.aio-nr Tue Oct 17 18:28:12 EDT 2017 fs.aio-nr = 129024 ubuntu@zm93k8:/home/scottg$ date;virsh start zs93kag70053 Tue Oct 17 18:29:38 EDT 2017 Domain zs93kag70053 started ubuntu@zm93k8:/home/scottg$ date;sysctl fs.aio-nr Tue Oct 17 18:29:42 EDT 2017 fs.aio-nr = 135168 ubuntu@zm93k8:/home/scottg$ date;virsh start zs93kag70054 Tue Oct 17 18:29:55 EDT 2017 Domain zs93kag70054 started ubuntu@zm93k8:/home/scottg$ date;sysctl fs.aio-nr Tue Oct 17 18:29:58 EDT 2017 fs.aio-nr = 141312 I saved dmesg output in case you need that. ubuntu@zm93k8:/home/scottg$ dmesg > dmesg.out.Oct17_bug157241 I will also keep this test environment up for a couple days in case you need additional data. Thank you. -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1717224 Title: virsh start of virtual guest domain fails with internal error due to low default aio-max-nr sysctl value Status in Ubuntu on IBM z Systems: In Progress Status in kvm package in Ubuntu: Confirmed Status in linux package in Ubuntu: In Progress Status in procps package in Ubuntu: New Status in kvm source package in Xenial: New Status in linux source package in Xenial: In Progress Status in procps source package in Xenial: New Status in kvm source package in Zesty: New Status in linux source package in Zesty: In Progress Status in procps source package in Zesty: New Status in kvm source package in Artful: Confirmed Status in linux source package in Artful: In Progress Status in procps source package in Artful: New Bug description: Starting virtual guests via on Ubuntu 16.04.2 LTS installed with its KVM hypervisor on an IBM Z14 system LPAR fails on the 18th guest with the following error: root@zm93k8:/rawimages/ubu1604qcow2# virsh start zs93kag70038 error: Failed to start domain zs93kag70038 error: internal error: process exited while connecting to monitor: 2017-07-26T01:48:26.352534Z qemu-kvm: -drive file=/guestimages/data1/zs93kag70038.qcow2,format=qcow2,if=none,id=drive-virtio-disk0,cache=none,aio=native: Could not open backing file: Could not set AIO state: Inappropriate ioctl for device The previous 17 guests started fine: root@zm93k8# virsh start zs93kag70020 Domain zs93kag70020 started root@zm93k8# virsh start zs93kag70021 Domain zs93kag70021 started . . root@zm93k8:/rawimages/ubu1604qcow2# virsh start zs93kag70036 Domain zs93kag70036 started We ended up fixing the issue by adding the following line to /etc/sysctl.conf : fs.aio-max-nr = 4194304 ... then, reload the sysctl config file: root@zm93k8:/etc# sysctl -p /etc/sysctl.conf fs.aio-max-nr = 4194304 Now, we're able to start more guests... root@zm93k8:/etc# virsh start zs93kag70036 Domain zs93kag70036 started The default value was originally set to 65535: root@zm93k8:/rawimages/ubu1604qcow2# cat /proc/sys/fs/aio-max-nr 65536 Note, we chose the 4194304 value, because this is what our KVM on System Z hypervisor ships as its default value. Eg. on our zKVM system: [root@zs93ka ~]# cat /proc/sys/fs/aio-max-nr 4194304 ubuntu@zm93k8:/etc$ lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 16.04.2 LTS Release: 16.04 Codename: xenial ubuntu@zm93k8:/etc$ ubuntu@zm93k8:/etc$ dpkg -s qemu-kvm |grep Version Version: 1:2.5+dfsg-5ubuntu10.8 Is something already documented for Ubuntu KVM users warning them about the low default value, and some guidance as to how to select an appropriate value? Also, would you consider increasing the default aio-max-nr value to something much higher, to accommodate significantly more virtual guests? Thanks! ---uname output--- ubuntu@zm93k8:/etc$ uname -a Linux zm93k8 4.4.0-62-generic #83-Ubuntu SMP Wed Jan 18 14:12:54 UTC 2017 s390x s390x s390x GNU/Linux Machine Type = z14 ---Debugger--- A debugger is not configured ---Steps to Reproduce--- See Problem Description. The problem was happening a week ago, so this may not reflect that activity. This file was collected on Aug 7, one week after we were hitting the problem. If I need to reproduce the problem and get fresh data, please let me know. /var/log/messages doesn't exist on this system, so I provided syslog output instead. All data have been collected too late after the problem was observed over a week ago. If you need me to reproduce the problem and get new data, please let me know. That's not a problem. Also, we would have to make special arrangements for login access to these systems. I'm happy to run traces and data collection for you as needed. If that's not sufficient, then we'll explore log in access for you. Thanks... - Scott G. I was able to successfully recreate the problem and captured / attached new debug docs. Recreate procedure: # Started out with no virtual guests running. ubuntu@zm93k8:/home/scottg$ virsh list Id Name State ---------------------------------------------------- # Set fs.aio-max-nr back to original Ubuntu "out of the box" value in /etc/sysctl.conf ubuntu@zm93k8:~$ tail -1 /etc/sysctl.conf fs.aio-max-nr = 65536 ## sysctl -a shows: fs.aio-max-nr = 4194304 ## Reload sysctl. ubuntu@zm93k8:~$ sudo sysctl -p /etc/sysctl.conf fs.aio-max-nr = 65536 ubuntu@zm93k8:~$ ubuntu@zm93k8:~$ sudo sysctl -a |grep fs.aio-max-nr fs.aio-max-nr = 65536 ubuntu@zm93k8:~$ cat /proc/sys/fs/aio-max-nr 65536 # Attempt to start more than 17 qcow2 virtual guests on the Ubuntu host. Fails on the 18th XML. Script used to start guests.. ubuntu@zm93k8:/home/scottg$ date;./start_privs.sh Wed Aug 23 13:21:25 EDT 2017 virsh start zs93kag70015 Domain zs93kag70015 started Started zs93kag70015 succesfully ... virsh start zs93kag70020 Domain zs93kag70020 started Started zs93kag70020 succesfully ... virsh start zs93kag70021 Domain zs93kag70021 started Started zs93kag70021 succesfully ... virsh start zs93kag70022 Domain zs93kag70022 started Started zs93kag70022 succesfully ... virsh start zs93kag70023 Domain zs93kag70023 started Started zs93kag70023 succesfully ... virsh start zs93kag70024 Domain zs93kag70024 started Started zs93kag70024 succesfully ... virsh start zs93kag70025 Domain zs93kag70025 started Started zs93kag70025 succesfully ... virsh start zs93kag70026 Domain zs93kag70026 started Started zs93kag70026 succesfully ... virsh start zs93kag70027 Domain zs93kag70027 started Started zs93kag70027 succesfully ... virsh start zs93kag70028 Domain zs93kag70028 started Started zs93kag70028 succesfully ... virsh start zs93kag70029 Domain zs93kag70029 started Started zs93kag70029 succesfully ... virsh start zs93kag70030 Domain zs93kag70030 started Started zs93kag70030 succesfully ... virsh start zs93kag70031 Domain zs93kag70031 started Started zs93kag70031 succesfully ... virsh start zs93kag70032 Domain zs93kag70032 started Started zs93kag70032 succesfully ... virsh start zs93kag70033 Domain zs93kag70033 started Started zs93kag70033 succesfully ... virsh start zs93kag70034 Domain zs93kag70034 started Started zs93kag70034 succesfully ... virsh start zs93kag70035 Domain zs93kag70035 started Started zs93kag70035 succesfully ... virsh start zs93kag70036 error: Failed to start domain zs93kag70036 error: internal error: process exited while connecting to monitor: 2017-08-23T17:21:47.131809Z qemu-kvm: -drive file=/guestimages/data1/zs93kag70036.qcow2,format=qcow2,if=none,id=drive-virtio-disk0,cache=none,aio=native: Could not open backing file: Could not set AIO state: Inappropriate ioctl for device Exiting script ... start zs93kag70036 failed ubuntu@zm93k8:/home/scottg$ # Show that there are only 17 running guests. ubuntu@zm93k8:/home/scottg$ virsh list |grep run |wc -l 17 ubuntu@zm93k8:/home/scottg$ virsh list Id Name State ---------------------------------------------------- 25 zs93kag70015 running 26 zs93kag70020 running 27 zs93kag70021 running 28 zs93kag70022 running 29 zs93kag70023 running 30 zs93kag70024 running 31 zs93kag70025 running 32 zs93kag70026 running 33 zs93kag70027 running 34 zs93kag70028 running 35 zs93kag70029 running 36 zs93kag70030 running 37 zs93kag70031 running 38 zs93kag70032 running 39 zs93kag70033 running 40 zs93kag70034 running 41 zs93kag70035 running # For fun, try starting zs93kag70036 again manually. ubuntu@zm93k8:/home/scottg$ date;virsh start zs93kag70036 Wed Aug 23 13:27:28 EDT 2017 error: Failed to start domain zs93kag70036 error: internal error: process exited while connecting to monitor: 2017-08-23T17:27:30.031782Z qemu-kvm: -drive file=/guestimages/data1/zs93kag70036.qcow2,format=qcow2,if=none,id=drive-virtio-disk0,cache=none,aio=native: Could not open backing file: Could not set AIO state: Inappropriate ioctl for device # Show the XML (they're all basically the same)... ubuntu@zm93k8:/home/scottg$ cat zs93kag70036.xml <domain type='kvm'> <name>zs93kag70036</name> <memory unit='MiB'>4096</memory> <currentMemory unit='MiB'>2048</currentMemory> <vcpu placement='static'>2</vcpu> <os> <type arch='s390x' machine='s390-ccw-virtio'>hvm</type> </os> <clock offset='utc'/> <on_poweroff>destroy</on_poweroff> <on_reboot>restart</on_reboot> <on_crash>preserve</on_crash> <devices> <emulator>/usr/bin/qemu-kvm</emulator> <disk type='file' device='disk'> <driver name ='qemu' type='qcow2' cache='none' io='native'/> <source file='/guestimages/data1/zs93kag70036.qcow2'/> <target dev='vda' bus='virtio'/> <address type='ccw' cssid='0xfe' ssid='0x0' devno='0x0000'/> <boot order='1'/> </disk> <interface type='network'> <source network='privnet1'/> <model type='virtio'/> <mac address='52:54:00:70:d0:36'/> <address type='ccw' cssid='0xfe' ssid='0x0' devno='0x0001'/> </interface> <!-- <disk type='block' device='disk'> <driver name ='qemu' type='raw' cache='none'/> <source dev='/dev/disk/by-id/dm-uuid-mpath-36005076802810e5540000000000006e4'/> <target dev='vde' bus='virtio'/> <address type='ccw' cssid='0xfe' ssid='0x0' devno='0x0005'/> <readonly/> </disk> --> <disk type='file' device='disk'> <driver name ='qemu' type='raw' cache='none' io='native'/> <source file='/guestimages/data1/zs93kag70036.prm'/> <target dev='vdf' bus='virtio'/> <address type='ccw' cssid='0xfe' ssid='0x0' devno='0x0006'/> </disk> <disk type='file' device='cdrom'> <driver name='qemu' type='raw'/> <source file='/guestimages/data1/zs93kag70036.iso'/> <target dev='sda' bus='scsi'/> <readonly/> <address type='drive' controller='0' bus='0' target='0' unit='0'/> </disk> <controller type='usb' index='0' model='none'/> <memballoon model='none'/> <console type='pty'> <target type='sclp' port='0'/> </console> </devices> </domain> This condition is very easy to replicate. However, we may be losing this system in the next day or two, so please let me know ASAP if you need any more data. Thank you... - Scott G. == Comment: #11 - Viktor Mihajlovski <mihaj...@de.ibm.com> - 2017-09-14 In order to support many KVM guests it is advisable to raise the aio-max-nr as suggested in the problem description, see also http://kvmonz.blogspot.co.uk/p/blog-page_7.html. I would also suggest that the system default setting is increased. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu-z-systems/+bug/1717224/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
