diff options
| author | Christian Krinitsin <mail@krinitsin.com> | 2025-05-30 16:52:07 +0200 |
|---|---|---|
| committer | Christian Krinitsin <mail@krinitsin.com> | 2025-05-30 16:52:17 +0200 |
| commit | 9260319e7411ff8281700a532caa436f40120ec4 (patch) | |
| tree | 2f6bfe5f3458dd49d328d3a9eb508595450adec0 /gitlab/issues_text/target_missing/host_missing/accel_missing/1139 | |
| parent | 225caa38269323af1bfc2daadff5ec8bd930747f (diff) | |
| download | qemu-analysis-9260319e7411ff8281700a532caa436f40120ec4.tar.gz qemu-analysis-9260319e7411ff8281700a532caa436f40120ec4.zip | |
gitlab scraper: download in toml and text format
Diffstat (limited to 'gitlab/issues_text/target_missing/host_missing/accel_missing/1139')
| -rw-r--r-- | gitlab/issues_text/target_missing/host_missing/accel_missing/1139 | 78 |
1 files changed, 78 insertions, 0 deletions
diff --git a/gitlab/issues_text/target_missing/host_missing/accel_missing/1139 b/gitlab/issues_text/target_missing/host_missing/accel_missing/1139 new file mode 100644 index 000000000..09b4e7c5b --- /dev/null +++ b/gitlab/issues_text/target_missing/host_missing/accel_missing/1139 @@ -0,0 +1,78 @@ +block/nbd.c and drive backup to a remote nbd server +Description of problem: +Good afternoon! + +I trying to copy attached drive content to remote NBD server via drive-backup QMP method. I'he tested two very similar ways but with very different performance. First is a backuping to exported NBD at another server. Second way is a backuping to same server but with connecting to /dev/nbd*. + +Exporting qcow2 via nbd: +``` +(nbd) ~ # qemu-nbd -p 12345 -x backup --cache=none --aio=native --persistent -f qcow2 backup.qcow2 + +(qemu) ~ # qemu-img info nbd://10.0.0.1:12345/backup +image: nbd://10.0.0.1:12345/backup +file format: raw +virtual size: 10 GiB (10737418240 bytes) +disk size: unavailable +``` + +Starting drive backuping via QMP: + +``` +{ + "execute": "drive-backup", + "arguments": { + "device": "disk", + "sync": "full", + "target": "nbd://10.0.0.1:12345/backup", + "mode": "existing" + } +} +``` + +With process starting qemu notifying about warning: + +> warning: The target block device doesn't provide information about the block size and it doesn't have a backing file. The default block size of 65536 bytes is used. If the actual block size of the target exceeds this default, the backup may be unusable + +And backup process is limited by speed around 30MBps, watched by iotop + + +Second way to creating backup + +Exporting qcow2 via nbd: +``` +(nbd) ~ # qemu-nbd -p 12345 -x backup --cache=none --aio=native --persistent -f qcow2 backup.qcow2 +``` + +``` +(qemu) ~ # qemu-img info nbd://10.0.0.1:12345/backup +image: nbd://10.0.0.1:12345/backup +file format: raw +virtual size: 10 GiB (10737418240 bytes) +disk size: unavailable +(qemu) ~ # qemu-nbd -c /dev/nbd0 nbd://10.0.0.1:12345/backup +(qemu) ~ # qemu-img info /dev/nbd0 +image: /dev/nbd0 +file format: raw +virtual size: 10 GiB (10737418240 bytes) +disk size: 0 B +``` + +Starting drive backuping via QMP to local nbd device: + +``` +{ + "execute": "drive-backup", + "arguments": { + "device": "disk", + "sync": "full", + "target": "/dev/nbd0", + "mode": "existing" + } +} +``` + +Backup process started without previous warning, and speed limited around 100MBps (network limit) + +So I have question: how I can get same performance without connection network device to local block nbd device at the qemu host? + +Kind regards |