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| author | Christian Krinitsin <mail@krinitsin.com> | 2025-05-21 21:21:26 +0200 |
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| committer | Christian Krinitsin <mail@krinitsin.com> | 2025-05-21 21:21:26 +0200 |
| commit | 4b927bc37359dec23f67d3427fc982945f24f404 (patch) | |
| tree | 245449ef9146942dc7fffd0235b48b7e70a00bf2 /gitlab/issues/target_missing/host_missing/accel_missing/1139.toml | |
| parent | aa8bd79cec7bf6790ddb01d156c2ef2201abbaab (diff) | |
| download | emulator-bug-study-4b927bc37359dec23f67d3427fc982945f24f404.tar.gz emulator-bug-study-4b927bc37359dec23f67d3427fc982945f24f404.zip | |
add gitlab issues in toml format
Diffstat (limited to 'gitlab/issues/target_missing/host_missing/accel_missing/1139.toml')
| -rw-r--r-- | gitlab/issues/target_missing/host_missing/accel_missing/1139.toml | 90 |
1 files changed, 90 insertions, 0 deletions
diff --git a/gitlab/issues/target_missing/host_missing/accel_missing/1139.toml b/gitlab/issues/target_missing/host_missing/accel_missing/1139.toml new file mode 100644 index 00000000..f501ac88 --- /dev/null +++ b/gitlab/issues/target_missing/host_missing/accel_missing/1139.toml @@ -0,0 +1,90 @@ +id = 1139 +title = "block/nbd.c and drive backup to a remote nbd server" +state = "closed" +created_at = "2022-08-03T09:26:02.923Z" +closed_at = "2024-05-13T12:24:52.546Z" +labels = ["block:nbd"] +url = "https://gitlab.com/qemu-project/qemu/-/issues/1139" +host-os = "Debian 10" +host-arch = "n/a" +qemu-version = "EMU emulator version 6.2.0 (Debian 1:6.2+dfsg-2~bpo11+1)" +guest-os = "n/a" +guest-arch = "n/a" +description = """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: + +``` +{ +\t"execute": "drive-backup", +\t"arguments": { +\t\t"device": "disk", +\t\t"sync": "full", +\t\t"target": "nbd://10.0.0.1:12345/backup", +\t\t"mode": "existing" +\t} +} +``` + +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: + +``` +{ +\t"execute": "drive-backup", +\t"arguments": { +\t\t"device": "disk", +\t\t"sync": "full", +\t\t"target": "/dev/nbd0", +\t\t"mode": "existing" +\t} +} +``` + +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""" +reproduce = "n/a" +additional = "n/a" |