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Re: [Qemu-devel] TRIM/DISCARD/UNMAP support on qemu-nbd
From: |
Richard W.M. Jones |
Subject: |
Re: [Qemu-devel] TRIM/DISCARD/UNMAP support on qemu-nbd |
Date: |
Tue, 7 Jan 2014 21:27:07 +0000 |
User-agent: |
Mutt/1.5.20 (2009-12-10) |
Using qcow2 format, it also doesn't appear to work:
$ /tmp/sparsetest.sh
Formatting '/tmp/test1', fmt=qcow2 size=104857600 encryption=off
cluster_size=65536 lazy_refcounts=off
Formatting '/tmp/test2', fmt=qcow2 size=104857600 encryption=off
cluster_size=65536 lazy_refcounts=off
136K /tmp/test1
136K /tmp/test2
Read Capacity results:
Protection: prot_en=0, p_type=0, p_i_exponent=0
Logical block provisioning: lbpme=1, lbprz=0
Last logical block address=204799 (0x31fff), Number of logical blocks=204800
Logical block length=512 bytes
Logical blocks per physical block exponent=0
Lowest aligned logical block address=0
Hence:
Device size: 104857600 bytes, 100.0 MiB, 0.10 GB
Block limits VPD page (SBC):
Write same no zero (WSNZ): 1
Maximum compare and write length: 0 blocks
Optimal transfer length granularity: 0 blocks
Maximum transfer length: 0 blocks
Optimal transfer length: 0 blocks
Maximum prefetch length: 0 blocks
Maximum unmap LBA count: 2097152
Maximum unmap block descriptor count: 255
Optimal unmap granularity: 8
Unmap granularity alignment valid: 0
Unmap granularity alignment: 0
Maximum write same length: 0x0 blocks
17M /tmp/test1
17M /tmp/test2
$ ll -h /tmp/test{1,2}
-rw-r--r--. 1 rjones rjones 17M Jan 7 21:24 /tmp/test1
-rw-r--r--. 1 rjones rjones 17M Jan 7 21:24 /tmp/test2
$ qemu-img info /tmp/test1
image: /tmp/test1
file format: qcow2
virtual size: 100M (104857600 bytes)
disk size: 16M
cluster_size: 65536
$ qemu-img info /tmp/test2
image: /tmp/test2
file format: qcow2
virtual size: 100M (104857600 bytes)
disk size: 16M
cluster_size: 65536
----------------------------------------------------------------------
A frustrating aspect of this is there's no diagnostics or way to probe
if UNMAP is supported all the way through.
This will be critical for virt-sparsify, since we'd like to be able to
tell the user in advance whether or not in-place sparsification is
going to work, and even better, why not.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
libguestfs lets you edit virtual machines. Supports shell scripting,
bindings from many languages. http://libguestfs.org
- Re: [Qemu-devel] TRIM/DISCARD/UNMAP support on qemu-nbd, Richard W.M. Jones, 2014/01/02
- Re: [Qemu-devel] TRIM/DISCARD/UNMAP support on qemu-nbd, Paolo Bonzini, 2014/01/07
- Re: [Qemu-devel] TRIM/DISCARD/UNMAP support on qemu-nbd, Richard W.M. Jones, 2014/01/07
- Re: [Qemu-devel] TRIM/DISCARD/UNMAP support on qemu-nbd, Paolo Bonzini, 2014/01/07
- Re: [Qemu-devel] TRIM/DISCARD/UNMAP support on qemu-nbd,
Richard W.M. Jones <=
- Re: [Qemu-devel] TRIM/DISCARD/UNMAP support on qemu-nbd, Richard W.M. Jones, 2014/01/07
- Re: [Qemu-devel] TRIM/DISCARD/UNMAP support on qemu-nbd, Paolo Bonzini, 2014/01/08
- Re: [Qemu-devel] TRIM/DISCARD/UNMAP support on qemu-nbd, Richard W.M. Jones, 2014/01/08
- Re: [Qemu-devel] TRIM/DISCARD/UNMAP support on qemu-nbd, Paolo Bonzini, 2014/01/08
- Re: [Qemu-devel] TRIM/DISCARD/UNMAP support on qemu-nbd, Richard W.M. Jones, 2014/01/08
- Re: [Qemu-devel] TRIM/DISCARD/UNMAP support on qemu-nbd, Paolo Bonzini, 2014/01/09