| Summary: | Thin provisioned block disk exceed its thin provisioned size once a dd operation is being executed on the guest VM | ||||||||||
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| Product: | [oVirt] vdsm | Reporter: | Maor <mlipchuk> | ||||||||
| Component: | Core | Assignee: | Maor <mlipchuk> | ||||||||
| Status: | CLOSED NOTABUG | QA Contact: | Aharon Canan <acanan> | ||||||||
| Severity: | unspecified | Docs Contact: | |||||||||
| Priority: | unspecified | ||||||||||
| Version: | 4.18.15 | CC: | amureini, bugs, mlipchuk | ||||||||
| Target Milestone: | ovirt-4.0.4 | Flags: | amureini:
ovirt-4.0.z?
rule-engine: planning_ack? rule-engine: devel_ack? rule-engine: testing_ack? |
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| Target Release: | --- | ||||||||||
| Hardware: | Unspecified | ||||||||||
| OS: | Unspecified | ||||||||||
| Whiteboard: | |||||||||||
| Fixed In Version: | Doc Type: | If docs needed, set a value | |||||||||
| Doc Text: |
Problem: A thin provisioned block disk might exceed its thin provisioned size.
Solution: The true size of the disk might exceed the thin provisioned size since qcow header's overhead is being allocated on a minimize block size which is 1 GB
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Story Points: | --- | ||||||||
| Clone Of: | Environment: | ||||||||||
| Last Closed: | 2016-08-28 16:02:51 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: | |||||||||
| Attachments: |
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Created attachment 1195055 [details]
The guest dd operation
Created attachment 1195056 [details]
vdsm log
Isn't this just the qcow header's overhead, coupled with the fact that we extend in 1GB chunks? (In reply to Allon Mureinik from comment #3) > Isn't this just the qcow header's overhead, coupled with the fact that we > extend in 1GB chunks? Yep, that is indeed the issue (although a bit misleading for customers) closing it as not a bug. |
Created attachment 1195054 [details] output of getVmDevice Description of problem: A VM's disk declare 6GB space although its virtual size is only 5 GB (The disk does not contain any snapshots). Creating a new VM with disk based on iSCSI with size of 5GB. Run the VM and install a RHEL 7.2 OS on it. Once the installation was finished use fdisk /dev/vda to find out which partitions are available and execute dd on the biggest partition. Version-Release number of selected component (if applicable): 4.0 How reproducible: 100% Steps to Reproduce: 1. Create a VM 2. Create a thin provision disk on iSCSI SD with 5 GB 3. Add a nic to the VM and edit the VM that the boot order will be first from network 4. Run the VM and install OS from network 5. log into the VM and execute dd with if=/dev/urandom and of is the VM device (/dev/vda2) Actual results: Once the dd operation is finished the true size of the VM reports 6GB although the virtual size is 5 GB Expected results: The true size should not exceed the virtual size of the disk which is 5 GB Additional info: