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[Bug 1884831] [NEW] qemu-nbd fails to discard bigger chunks
From: |
TobiasHunger |
Subject: |
[Bug 1884831] [NEW] qemu-nbd fails to discard bigger chunks |
Date: |
Tue, 23 Jun 2020 20:19:41 -0000 |
Public bug reported:
This report is moved from systemd to here:
https://github.com/systemd/systemd/issues/16242
A qemu-nbd device reports that it can discard a lot of bytes:
cat /sys/block/nbd0/queue/discard_max_bytes
2199023255040
And indeed, discard works with small images:
$ qemu-img create -f qcow2 /tmp/image.img 2M
$ sudo qemu-nbd --connect=/dev/nbd0 /tmp/image.img
$ sudo blkdiscard /dev/nbd0
but not for bigger ones (still smaller than discard_max_bytes):
$ qemu-img create -f qcow2 /tmp/image.img 5G
$ sudo qemu-nbd --connect=/dev/nbd0 /tmp/image.img
$ sudo blkdiscard /dev/nbd0
** Affects: qemu
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1884831
Title:
qemu-nbd fails to discard bigger chunks
Status in QEMU:
New
Bug description:
This report is moved from systemd to here:
https://github.com/systemd/systemd/issues/16242
A qemu-nbd device reports that it can discard a lot of bytes:
cat /sys/block/nbd0/queue/discard_max_bytes
2199023255040
And indeed, discard works with small images:
$ qemu-img create -f qcow2 /tmp/image.img 2M
$ sudo qemu-nbd --connect=/dev/nbd0 /tmp/image.img
$ sudo blkdiscard /dev/nbd0
but not for bigger ones (still smaller than discard_max_bytes):
$ qemu-img create -f qcow2 /tmp/image.img 5G
$ sudo qemu-nbd --connect=/dev/nbd0 /tmp/image.img
$ sudo blkdiscard /dev/nbd0
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1884831/+subscriptions
- [Bug 1884831] [NEW] qemu-nbd fails to discard bigger chunks,
TobiasHunger <=
- Re: [Bug 1884831] [NEW] qemu-nbd fails to discard bigger chunks, Eric Blake, 2020/06/23
- [Bug 1884831] Re: qemu-nbd fails to discard bigger chunks, Eric Blake, 2020/06/23
- [Bug 1884831] [NEW] qemu-nbd fails to discard bigger chunks, Launchpad Bug Tracker, 2020/06/23
- [Bug 1884831] Re: qemu-nbd fails to discard bigger chunks, Eric Blake, 2020/06/23
- [Bug 1884831] Re: qemu-nbd fails to discard bigger chunks, Eric Blake, 2020/06/23