Following on from the recent (November 2015) ESXi 6.0 CBT bug, which has now been fixed in the latest released patch ESXi600-201511401-BG, some further information has come to light, provided by Anton Gostev, of Veeam.
You can read the snippet of important information from the Veeam forum post following the issue (Official Veeam KB2075);
All, we have completed the first day of testing in the same exact lab and using the same heavy write I/O test that made the original issue easily reproducible. After a few TB of increments, the above-mention patch appears to fully resolve the original issue when installed on ESX 6.0 Update 1a build 3073146.
However, we found that simply installing the patch is not sufficient,and CBT reset is required for all of your VMs. This is because existing CBT map files may contain issues created earlier due to the original bug, which may result in inconsistent full backups in future. Having CBT reset will also force the following job run use "full scan" incremental pass, thus fixing any existing inconsistencies in backups and replicas, as discussed earlier in this topic.
Provided CBT reset has been performed, Active Full backups is not required.
Performing Active Full backups by itself cannot be considered as a substitute to CBT reset with this particular CBT issue.
Firmware WB.15.18.0007 resolves the issue, see below
A colleague of mine found an issue with the latest HP 2920 switch firmware.
If you create VLANs using the CLI Menu, the switch reboots and the configuration is not saved.
We have reported this to HP, but is currently being treated as a non critical issue as when creating a VLAN via the web interface or native CLI, the issue doesn’t happen.
We have also noticed on this firmware the switch seems to be less responsive. Luckily we had a few units in stock that we could replicate this issue on, and can confirm downgrading to the previous firmware version removes the issue.
A quick cheers to my colleague Marco for finding and researching this issue.
Switch: HP 2920-48G-POE+
Primary Image : 12852982 08/12/15 WB.15.18.0006
Software revision : WB.15.18.0006
Go to the Main Menu
Select (2) Switch Configuration…
Select (8) VLAN Menu…
Select (3) VLAN Port Assignment
Modify the tagging mode for a port
Switch reboots and doesn’t save configuration
Hopefully HP will release a fix for this firmware soon, as mentioned we have recreated this issue in production and test.
So here we are again, rounding the year off with yet another change block tracking warning.
I’ve written posts previously on the CBT bugs found in 5.5 and below and those found when vSphere 6.0 was released into the wild.
So whats the issue this time?
Basically it is the same as last time, the wrong sectors of data locations are returned by CBT when requested by your backup software. Meaning it targets the wrong data to backup.
Here is the official VMware KB 2136854. Which describes the following;
When running virtual machine backups which utilize Changed Block Tracking (CBT) in ESXi 6.0, you experience these symptoms:
- The CBT API call QueryDiskChangedAreas() API call can sometimes return incorrect changed sectors, which results in inconsistent incremental virtual machine backups.
- Inconsistent virtual machine backups
All incremental backups which utilize CBT are potentially affected.
Today I’ve noticed that when using the vCenter C# client, each VM shows up as allowing for “Revert to current snapshot” and “Consolidation” however there is no open snapshot on the virtual machine.
Above we can see clearly the options to “Revert …” and “Consolidate” are available, but when looking at Snapshot Manager, they are is nothing apparent.
Looking into the configuration of the VM, there is no number string appended to the file name for the hard drive, i.e -00000001.vmdk as you would usually see for hard drives of a VM that is running on a snapshot
If I bite the bullet and try to revert the snapshot or consolidate the VM, the vCenter task comes straight away, but the options are still available.
Logging into the Web Client, you can see these options are not available for the VM.
This means that it must be a GUI based bug in the application. As VMware are trying to phase out the application, I am not sure if they will resolve it.
Update – it is a known issue
Frank Buchsel is a Technical Support Engineer for VMware, and his blog is brilliant! I urge you to check it out.