Bug 1122830
| Summary: | qemu-img convert doesn't print "No space left on device" strings error when the destination lv has no enough space | |||
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| Product: | Red Hat Enterprise Linux 7 | Reporter: | Sibiao Luo <sluo> | |
| Component: | qemu-kvm-rhev | Assignee: | Hanna Czenczek <hreitz> | |
| Status: | CLOSED NOTABUG | QA Contact: | Virtualization Bugs <virt-bugs> | |
| Severity: | medium | Docs Contact: | ||
| Priority: | medium | |||
| Version: | 7.0 | CC: | hhuang, juzhang, virt-maint | |
| Target Milestone: | rc | |||
| Target Release: | --- | |||
| Hardware: | Unspecified | |||
| OS: | Unspecified | |||
| Whiteboard: | ||||
| Fixed In Version: | Doc Type: | Bug Fix | ||
| Doc Text: | Story Points: | --- | ||
| Clone Of: | ||||
| : | 1122847 (view as bug list) | Environment: | ||
| Last Closed: | 2014-07-24 23:10:14 UTC | Type: | Bug | |
| Regression: | --- | Mount Type: | --- | |
| Documentation: | --- | CRM: | ||
| Verified Versions: | Category: | --- | ||
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | ||
| Cloudforms Team: | --- | Target Upstream Version: | ||
| Embargoed: | ||||
| Bug Depends On: | ||||
| Bug Blocks: | 1122847 | |||
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Description
Sibiao Luo
2014-07-24 07:47:41 UTC
# lvdisplay /dev/vg/lv1 --- Logical volume --- LV Path /dev/vg/lv1 LV Name lv1 VG Name vg LV UUID P8zOCk-QILD-AKaV-mon0-CT9F-c76r-8FPBB3 LV Write Access read/write LV Creation host, time dhcp-11-154.nay.redhat.com, 2014-07-24 15:06:41 +0800 LV Status available # open 0 LV Size 10.00 GiB Current LE 2560 Segments 1 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 253:3 # lvdisplay /dev/vg/lv2 --- Logical volume --- LV Path /dev/vg/lv2 LV Name lv2 VG Name vg LV UUID tlp3RM-sQGW-vs8O-6std-3ECf-IO65-MUoiDe LV Write Access read/write LV Creation host, time dhcp-11-154.nay.redhat.com, 2014-07-24 15:06:50 +0800 LV Status available # open 0 LV Size 4.00 GiB Current LE 1024 Segments 1 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 253:4 Hi, Without filling lv1 (dd if=/dev/zero of=/dev/vg/lv1 bs=16M count=1) I in fact get the error message you expected (kernel 3.14.8-200.fc20.x86_64, both with RHEL 6's and RHEL 7's qemu): $ lvcreate -L 16M -n lv1 vg $ lvcreate -L 4M -n lv2 vg $ ./qemu-img convert -p -f raw -O qcow2 /dev/vg/lv1 /dev/vg/lv2 error while writing sector 4096: No space left on device With having used dd if=/dev/zero before, the error message disappears. However, interestingly, when using /dev/urandom instead of /dev/zero, the message reappears. Therefore, I saved the qcow2 image somewhere else and checked its size: $ dd if=/dev/urandom of=/dev/vg/lv1 bs=16M count=1 $ ./qemu-img convert -f raw -O qcow2 /dev/vg/lv1 foo.qcow2 $ ls -lh foo.qcow2 -rw-r--r--. 1 root root 17M 25. Jul 01:02 foo.qcow2 $ dd if=/dev/zero of=/dev/vg/lv1 bs=16M count=1 $ ./qemu-img convert -f raw -O qcow2 /dev/vg/lv1 foo.qcow2 $ ls -lh foo.qcow2 -rw-r--r--. 1 root root 193K 25. Jul 01:02 foo.qcow2 $ ./qemu-img map foo.qcow2 Offset Length Mapped to File And indeed, qemu-img's img_convert() checks whether the read data is zero (through is_allocated_sectors_min()) and only writes to the output if it is. Thus, the resulting qcow2 file is very small and indeed fits into the smaller volume. Max # lvscan | grep /dev/vg/
ACTIVE '/dev/vg/lv1' [100.00 MiB] inherit
ACTIVE '/dev/vg/lv2' [20.00 MiB] inherit
# qemu-img create -f qcow2 /dev/vg/lv2 20M
Formatting '/dev/vg/lv2', fmt=qcow2 size=20971520 encryption=off cluster_size=65536 lazy_refcounts=off
# qemu-img info /dev/vg/lv1
image: /dev/vg/lv1
file format: raw
virtual size: 100M (104857600 bytes)
disk size: 0
# qemu-img info /dev/vg/lv2
image: /dev/vg/lv2
file format: qcow2
virtual size: 20M (20971520 bytes)
disk size: 0
cluster_size: 65536
Format specific information:
compat: 1.1
lazy refcounts: false
# dd if=/dev/urandom of=/dev/vg/lv1 bs=1M
dd: error writing ‘/dev/vg/lv1’: No space left on device
101+0 records in
100+0 records out
104857600 bytes (105 MB) copied, 10.8566 s, 9.7 MB/s
# qemu-img convert -p -f raw -O qcow2 /dev/vg/lv1 /dev/vg/lv2
qemu-img: error while writing sector 36864: No space left on device
Best Regards,
sluo
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