Ditto for Qcow2. We use it on ZFS. I do a snapshot-create-as to get the QCOW2 consistent image, then zfs snapshot, then replicate to another host for backups. All the VMS have consistent backups in this way.
On 11/7/2017 5:16 AM, Vasiliy Tolstov wrote: > Please don't use lvm thin for vm. In our hosting in Russia we have > 100-150 vps on each node with lvm thin pool on ssd and have locks, > slowdowns and other bad things because of COW. After we switching to > qcow2 files on plain ssd ext4 fs and happy =). > > > 2017-11-04 23:21 GMT+03:00 Jan Hutař <jhu...@redhat.com>: >> Hello, >> as usual, I'm few years behind trends so I have learned about LVM thin >> volumes recently and I especially like that your volumes can be "sparse" >> - that you can have 1TB thin volume on 250GB VG/thin pool. >> >> Is it somehow possible to use that with libvirt? >> >> I have found this post from 2014: >> >> https://www.redhat.com/archives/libvirt-users/2014-August/msg00010.html >> >> which says you should be able to create "sparse" volume with `virsh >> vol-create ...` or that libvirt should be able to see thin volumes you >> create yourself, but neither of that works for me >> (libvirt-3.2.1-6.fc26.x86_64). >> >> This way I try to create new: >> >> # vgs storage >> VG #PV #LV #SN Attr VSize VFree >> storage 1 1 0 wz--n- 267.93g 0 # lvs storage -a >> LV VG Attr LSize Pool Origin Data% Meta% >> Move Log Cpy%Sync Convert >> [lvol0_pmspare] storage ewi------- 68.00m >> lvol1 storage twi-aotz-- 267.80g 0.00 0.44 >> [lvol1_tdata] storage Twi-ao---- 267.80g >> [lvol1_tmeta] storage ewi-ao---- 68.00m >> # virsh pool-dumpxml storage >> <pool type='logical'> >> <name>storage</name> >> <uuid>f523aed2-a7e4-4dc2-88db-0193a7337704</uuid> >> <capacity unit='bytes'>287687311360</capacity> >> <allocation unit='bytes'>287687311360</allocation> >> <available unit='bytes'>0</available> >> <source> >> <device path='/dev/nvme0n1p3'/> >> <name>storage</name> >> <format type='lvm2'/> >> </source> >> <target> >> <path>/dev/storage</path> >> </target> >> </pool> >> # cat /tmp/big.xml >> <volume> >> <name>big</name> >> <capacity>1073741824</capacity> >> <allocation>1048576</allocation> >> <target> >> <path>/dev/storage/big</path> >> </target> >> </volume> >> # virsh vol-create storage /tmp/big.xml error: Failed to create vol >> from /tmp/big.xml >> error: internal error: Child process (/usr/sbin/lvcreate --name big -L >> 1024K --type snapshot --virtualsize 1048576K storage) unexpected exit status >> 5: Volume group "storage" has insufficient free space (0 extents): 1 >> required. >> >> When I create thin volume manually, I do not see it: >> >> # lvcreate -n big -V 500G --thinpool storage/lvol1 >> Using default stripesize 64.00 KiB. >> WARNING: Sum of all thin volume sizes (500.00 GiB) exceeds the size of >> thin pool storage/lvol1 and the size of whole volume group (267.93 GiB)! >> For thin pool auto extension activation/thin_pool_autoextend_threshold >> should be below 100. >> Logical volume "big" created. >> # lvs storage -a >> LV VG Attr LSize Pool Origin Data% Meta% >> Move Log Cpy%Sync Convert >> big storage Vwi-a-tz-- 500.00g lvol1 0.00 >> [lvol0_pmspare] storage ewi------- 68.00m >> lvol1 storage twi-aotz-- 267.80g 0.00 0.45 >> [lvol1_tdata] storage Twi-ao---- 267.80g >> [lvol1_tmeta] storage ewi-ao---- 68.00m >> # virsh vol-list storage >> Name Path >> ------------------------------------------------------------------------------ >> >> >> Do I understand the concept incorrectly, or is there something else to >> configure? >> >> At the end I want to get max IO performance with possibility to >> "overcommit disk space". I know I can use storage "dir", but thought >> there might be something faster? >> >> Thank you very much for a response, >> Jan >> >> >> >> -- >> Jan Hutar Systems Management QA >> jhu...@redhat.com Red Hat, Inc. >> >> _______________________________________________ >> libvirt-users mailing list >> libvirt-users@redhat.com >> https://www.redhat.com/mailman/listinfo/libvirt-users > > -- Doug Hughes Keystone NAP Fairless Hills, PA 1.844.KEYBLOCK (539.2562)
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