Note: This bug is displayed in read-only format because the product is no longer active in Red Hat Bugzilla.
RHEL Engineering is moving the tracking of its product development work on RHEL 6 through RHEL 9 to Red Hat Jira (issues.redhat.com). If you're a Red Hat customer, please continue to file support cases via the Red Hat customer portal. If you're not, please head to the "RHEL project" in Red Hat Jira and file new tickets here. Individual Bugzilla bugs in the statuses "NEW", "ASSIGNED", and "POST" are being migrated throughout September 2023. Bugs of Red Hat partners with an assigned Engineering Partner Manager (EPM) are migrated in late September as per pre-agreed dates. Bugs against components "kernel", "kernel-rt", and "kpatch" are only migrated if still in "NEW" or "ASSIGNED". If you cannot log in to RH Jira, please consult article #7032570. That failing, please send an e-mail to the RH Jira admins at rh-issues@redhat.com to troubleshoot your issue as a user management inquiry. The email creates a ServiceNow ticket with Red Hat. Individual Bugzilla bugs that are migrated will be moved to status "CLOSED", resolution "MIGRATED", and set with "MigratedToJIRA" in "Keywords". The link to the successor Jira issue will be found under "Links", have a little "two-footprint" icon next to it, and direct you to the "RHEL project" in Red Hat Jira (issue links are of type "https://issues.redhat.com/browse/RHEL-XXXX", where "X" is a digit). This same link will be available in a blue banner at the top of the page informing you that that bug has been migrated.

Bug 806312

Summary: block stream touches all qcow2 image cluster
Product: Red Hat Enterprise Linux 6 Reporter: Shaolong Hu <shu>
Component: qemu-kvmAssignee: Virtualization Maintenance <virt-maint>
Status: CLOSED NOTABUG QA Contact: Virtualization Bugs <virt-bugs>
Severity: medium Docs Contact:
Priority: medium    
Version: 6.3CC: acathrow, bsarathy, juzhang, kwolf, michen, mkenneth, 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: Environment:
Last Closed: 2012-03-23 13:41:04 UTC Type: ---
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: 806280    

Description Shaolong Hu 2012-03-23 12:16:46 UTC
Description of problem:
------------------------
After block stream, qcow2 image disk size reaches to virtual size.


Version-Release number of selected component (if applicable):
-------------------------------------------------------------
qemu-kvm-0.12.1.2-2.262.el6rhev.x86_64


How reproducible:
-----------------
100%


Steps to Reproduce:
--------------------
1.(qemu) info block
drive-virtio-disk0: removable=0 io-status=ok file=/root/RHEL-Server-6.3-64-virtio.qcow2 ro=0 drv=qcow2 encrypted=0

2.(qemu) snapshot_blkdev drive-virtio-disk0 /root/sn1 qcow2

3.(qemu) block_stream drive-virtio-disk0

4.[root@shu ~]# qemu-img info sn1
image: sn1
file format: qcow2
virtual size: 20G (21474836480 bytes)
disk size: 20G
cluster_size: 65536

5.[root@shu ~]# qemu-img info RHEL-Server-6.3-64-virtio.qcow2 
image: RHEL-Server-6.3-64-virtio.qcow2
file format: qcow2
virtual size: 20G (21474836480 bytes)
disk size: 4.5G
cluster_size: 65536

  
Expected results:
------------------
Hi, i am not sure whether this is a bug, if not, please explain a little bit, and i highly recommend this as a RFE if can not be solved in 6.3, for streaming is mainly used by customer to update or re-arrange their storage, they probably don't want to see that after migrating to a larger storage, there is still no space left.

Comment 2 Kevin Wolf 2012-03-23 13:41:04 UTC
This is expected, only QED supports streaming efficiently today. We will fix this with an image format extension ("qcow3") in RHEL 7.