2015/01/12

Veeam v8 Forever Incremental

With the release of v8 a new backup method has been introduced, called forever incremental. Not a lot of fuzz around it but still a nice feature:
  • First of all, the method first creates an increment in a similar way as the traditional forward incremental. The big advantages over reverse incremental is that creating a VIB file is fairly sequential. Thus the snapshot on the target VM will be removed earlier then with reverse incremental. What is important is that overall job time might be higher, because the merge process might take longer, but the impact on production is lower.
  • The forever incremental job uses the same mechanism as the backup copy job for respecting the backup retention policy. First it creates the VIB file. Once the retention points are satisfied, it will inject the oldest VIB file in the VBK file. Again this process is fairly random but should be 33% less I/O then reverse incremental backup during merge and it is performed after the snapshots are deleted on the VM.
  • Because there is only 1 full VBK file, it uses less disk storage and only stores incremental data.
What is important is that there is still random I/O, if some job is merging and another on is still in the backup process, the later one might be impacted if you are backing up to the same spindles. Still the I/O penalty is lower (3 vs 2 I/O's).

So how do you configure it? Well you just select incremental mode and disable any synthetic or active full backups like so. If you would do this in v7, the GUI will complain you are not doing any full backups, in v8 it will switch to forever incremental


Configuring is quite easy. Now a lot of customers have asked, how can we do active fulls? Well if you configure active full backups, you are basically disabling forever incremental, thus the job won't do any merging. It is also why it is called, forever incremental.

There are some good reasons why you want to do an active full every month or every 2 months. First of all corruption. However, with Veeam, it is highly recommended to use Surebackup to execute recovery tests. In v7, a new option has been added to verify all the blocks (or the complete backup file). You can find this option, in the settings tab of of the Surebackup job. When in doubt, check the manual

If you do not run Surebackup, in v7 a manual tool was introduced "Veeam.Backup.Validator.exe". You can read more about it on Luca's blog

 In v8 this tool has been extended so you can run it on backups that are not even imported in B&R. Also you can output the report to an XML file, which should allow you to script around it. For example:
Veeam.Backup.Validator.exe /file:'V:\Backup\Backup Job Linux\Backup Job Linux.vbm' /format:xml /report:V:\linux.xml
Then with powershell, it is really easy to read out the values. Maybe the parameters might be a bit more difficult but here is an example.
param(
 $validator = "C:\Program Files\Veeam\Backup and Replication\Backup\Veeam.Backup.Validator.exe",
 $resultfile = [System.IO.Path]::GetTempFileName(),
 $backupfile = "V:\Backup\Backup Job Linux\Backup Job Linux.vbm"
)

&$validator ("/file:{0}" -f $backupfile) ("/report:{0}" -f $resultfile) "/format:xml" "/silence"


$result = [xml]$(Get-Content $resultfile)
write-host ("Result {0}" -f $result.Report.ResultInfo.Result)
write-host ("Checked {0}" -f $result.SelectSingleNode("//Parameter[@Name='Backup files count:']").InnerText)
Watch out, I tried to run the example via the powershell_ise, and the validator didn't spit out correct result. Running it manually seems to work. Also the validator seems to only check the last restore point. Instead of specifying the VBM file you can also specify the VBK file so the check will be done on this specific file.



Ok so validation (or healtcheck like it is called for a backup copy job) is not an issue. Apparently fragmentation of the backup file has been enhanced greatly as well in v8. However there is one thing you can not do in Windows, and that is shrinks files. Imagine you backup 10 VM's today but in a couple of weeks, after a migration, 2 VM's are being deleted. You might have archived them so they are no longer in production and thus are not being backed up anymore. Well the unique blocks of the VM's are being marked as deleted but the VBK file will never become smaller. When Veeam needs to store or inject more data, it will try to reuse those "blocks" or "empty space", but the file never shrinks. For a backup copy job, a method call "compacting" was introduced. It recreates the VBK file and skips empty blocks. However this methos is not (yet?) available for a normal backup job. Thus the only way to accomplish is this is to do an active full.

However, like discussed, if you enable active full in the scheduler, the backup job will switch back to the v7 forward incremental style and will not merge anything. The solution? Run an active full once in a while manually, or create a small powershell script. the script itself can be rather small like:
asnp veeampssnapin
Get-VBRJob -name "Backup Job Linux" | Start-VBRJob -FullBackup
You could schedule this for example every 2 months. If you need help scheduling, check out my previous blog post

What is important is that because you execute an active full your potential retention length might be 2x your retention policy before the previous chain is deleted. What does this mean in plain English? Well imagine if you configured 3 retention points. After a while you execute an active full. You will have the following situation

 

However at this point, nothing is being deleted because the active full starts a new backup chain. So nothing will be deleted until this new chain has 3 retention points.


2 comments:

  1. if you upgrade frm v7 , must you run an active full to make the forward forever incremental active, or just upgrade to v8 and activate the setting to have a forward forever incremental?

    ReplyDelete
  2. Now we have one problem with using Veeam 8. We got the file size of full backup (.vbk) almost as same as the file size of incremental backup(.vib). Why? Give us some advices, thanks a lot.

    ReplyDelete