Bug 1318050

Summary: Livemerge Cannot remove Snapshot. Low disk space on Storage Domain
Product: [oVirt] ovirt-engine Reporter: md
Component: BLL.StorageAssignee: Ala Hino <ahino>
Status: CLOSED CURRENTRELEASE QA Contact: Aharon Canan <acanan>
Severity: high Docs Contact:
Priority: high    
Version: 3.6.3.3CC: acanan, ahino, amureini, bugs, mgoldboi, sbonazzo, tnisan, ylavi
Target Milestone: ovirt-3.6.6Flags: rule-engine: ovirt-3.6.z+
rule-engine: blocker+
ylavi: planning_ack+
tnisan: devel_ack+
acanan: testing_ack+
Target Release: 3.6.6.2   
Hardware: x86_64   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Cause: Wrong storage allocation validation - we checked allocation both for disks and snapshots Consequence: Fail to live merge snapshots Fix: For live merge, we only want to check allocation for disks Result: Live merge snapshots will not fail due storage allocation validation
 Story Points: ---
Clone Of: Environment:
Last Closed: 2016-05-26 18:30:11 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: Storage RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description md 2016-03-15 21:32:21 UTC 
Description of problem:

when you try to delete a Snapshot which has a parent disk bigger than the remaining Space in the Storage Pool, the request fails with:

Cannot remove Snapshot. Low disk space on Storage Domain

Version-Release number of selected component (if applicable):

ovirt-engine-3.6.3.4-1.el7.centos.noarch
vdsm-4.17.24-0.el7.centos.noarch

How reproducible:

always

Steps to Reproduce:
1.create am VM with a Disk preallocated bigger than 50% of the remaining
Space in the Storage Domain
2.create a live Snapshot
3.try to delete the Snapshot live.

Actual results:

Snaphot will not be deleted, because not enought Space is available to completely copy the whole Disk to a new one (which is still the behaviour of offline Snapshot Deletion)

Expected results:

Snapshot will be deleted, because no Storage Extension is required with live merge / blockcommit anymore

Additional info:

I think the Problem is that the calcution of the required free Space is still using the offline Snapshot restrictions. This behaviour is a Problem when you use Snapshots for backing up big VMs (Fileserver etc.) as you always required the double Space of the VM in the Pool, but this Space cannot be used for VM disks.
Comment 1 Tal Nisan 2016-03-16 09:51:35 UTC 
Vered, as storage space validations was your feature, can you please have a look?
Comment 2 Yaniv Kaul 2016-05-04 19:15:03 UTC 
Reason for requesting a blocker:
It renders the merge operation impossible in case of extremely large disks when a small snapshot was made for backup purposes, cold merge will sometimes will not be possible due to disk space restrictions leaving live merge as the only option since it only requires a space equal to the small snapshot size rather than the big base image."

QE - ACK?
Comment 3 Allon Mureinik 2016-05-05 09:05:00 UTC 
Ala, as this is a user facing issue, please add some doctext to explain this bugfix.
Comment 4 Ori Gofen 2016-05-11 10:49:44 UTC 
verified on rhevm-3.6.5.3-0.1.el6.noarch.
this operation is now blocked due to lack of space on the target storage domain, oVirt's ui prompts the user with a pop up warning.
Comment 5 md 2016-05-18 20:52:44 UTC 
Tested with ovirt-engine-3.6.6.2-1.el7.centos.noarch, seems to be fixed.
Comment 7 Allon Mureinik 2016-05-26 18:30:11 UTC 
(In reply to md from comment #5)
> Tested with ovirt-engine-3.6.6.2-1.el7.centos.noarch, seems to be fixed.
Not sure why this wasn't moved automatically, but it's indeed fixed, closing.