[Qemu-devel] qcow2 disk size information may be error while it is larger than 2T capacity

[Qemu-devel] qcow2 disk size information may be error while it is larger than 2T capacity

[Guozhonghua]

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Hi, everyone

We have one qemu image file which size is 2348439044096, format is qcow2.
But as we get its information with the command qemu-img info, the disk size is 139G.
The info is as below:

# qemu-img info APCD-CSSJK
image: APCD-CSSJK
file format: qcow2
virtual size: 1.9T (2097152000000 bytes)
disk size: 139G
cluster_size: 2097152
backing file:  /vms/storage/APCD-JHSJK_base_0

# qemu-img info APCD-JHSJK_base_0
image: APCD-JHSJK_base_0
file format: qcow2
virtual size: 1.0T (1101004800000 bytes)
disk size: 34G
cluster_size: 2097152

# ls -al APCD-JHSJK_base_0
-rw-r--r-- 1 root root 36012294144 Aug  9 00:31 APCD-JHSJK_base_0
root@HZ-CAS01-CVK01: /vms/storage# ls -al APCD-CSSJK
-rw------- 1 root root 2348439044096 Aug 19 17:36 APCD-CSSJK

As calculated with the image size, so the information of the disk size display may be wrong:
(2348439044096 - 2*1024*1024*1024*1024) /( 1024*1024*1024) = 139.154296875 G

As we convert the APCD-CSSJK with -O qcow2, the destination image is larger then 500G, which is larger than 139G + 36G; and we stop the converting.
qemu-img convert -O qcow2 APCD-CSSJK apcd_csscssjk-gzh

# ls -al apcd* ;date
-rw-r--r-- 1 root root 483043311616 Aug 19 20:01 apcd_csscssjk-gzh
Tue Aug 19 20:01:34 CST 2014

# qemu-img info apcd_csscssjk-gzh
image: apcd_csscssjk-gzh
file format: qcow2
virtual size: 1.9T (2097152000000 bytes)
disk size: 469G
cluster_size: 2097152

Is the disk size segment is limited to 2T in qemu? Or there are some patch for it.

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Re: [Qemu-devel] qcow2 disk size information may be error while it is larger than 2T capacity

[Stefan Hajnoczi]

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On Thu, Aug 21, 2014 at 08:26:58AM +0000, Guozhonghua wrote:
> Hi, everyone
> 
> We have one qemu image file which size is 2348439044096, format is qcow2.
> But as we get its information with the command qemu-img info, the disk size is 139G.
> The info is as below:
> 
> # qemu-img info APCD-CSSJK
> image: APCD-CSSJK
> file format: qcow2
> virtual size: 1.9T (2097152000000 bytes)
> disk size: 139G
> cluster_size: 2097152
> backing file:  /vms/storage/APCD-JHSJK_base_0

Please post the output of stat --format "%b %B" APCD-CSSJK

Stefan

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