edit SOBR "performance tier" & "placement policy" screens when extent offline contradictory

[edison5000]

case 06225696

So between the two screens here in Edit SOBR, it appears that one checkbox if checked (or not) would contradict the other. Which takes precedence?

By this I mean

"perform full backup when the required extent is offline" vs "strict placement policy enforcement"

?

https://imgur.com/a/o6vyU0L

[tyler.jurgens]

"perform full backup when the required extent is offline"
This assumes you have multiple extents in the SOBR. How else are you going to take a backup if the only extent is down? This only comes into play if the one extent those backups usually target is offline.

"strict placement policy enforcement"
This happens when you have multiple extents in a SOBR (all online) and one extent gets too full to accommodate more backups. If that checkbox is not selected, the vibs will be created on another extent. If that checkbox is selected, the jobs will fail.

Note: All active full backups targeting a SOBR will go through a SOBR extent selection process - that is to say, if you have one job backing up for a long time on extent A, and then decide to take an active full backup, you may see that new VBK and subsequent VIBs target extent B (or C, or D, etc). They may target extent A as well. But they will go through an extent selection process. Data locality only means that every full backup and incrementals will try to target the same extent (unless you run into space constraints, as mentioned above).

[edison5000]

I think I'm still misunderstanding something (super obvious then?) in the descriptions of these two items. : ) It sure looks to me like they will behave the same way if an extent goes offline, which is why they look redundant or contradictory to me.

In our setup here, we have Data Locality turned on for our single B&R server with single local SOBR, with two extents.

A few weeks ago, before we upgraded to v12 from v11a, one of the extents went offline and we didn't notice it for a day or so, for reasons. As a result, all the jobs that failed in v11 to go to their "home" extent, started doing new fulls on the remaining live extent. Even though we've taken steps to prevent the same failure and lack of notification in the future, we would prefer to stop jobs from trying to backup to the remaining online extent. So clearly one or both of these checkboxes will do that job.

[tyler.jurgens]

If you want to avoid that scenario, uncheck "perform full backup when the required extent is offline".

Strict placement policy matters when your extent is full, not when your extent is offline. Without "perform full backup when the required extent is offline" enabled, jobs will fail if an extent goes offline, even if strict placement policy is unchecked.

Strict placement policy cares about existing backup chains. Eg: You have a Full on Sunday, an Incremental on Tuesday, and an Incremental on Wednesday all on Extent A. Come Thursday you do not have any more space on Extent A to create a new incremental. Without strict placement policy, an Incremental will be created on Thursday on Extent B, continuing the existing backup chain on Extent B. If strict placement policy is enabled, the Thursday backup will fail.

With "perform full backup when the required extent is offline" enabled, nothing changes if both extents are online. Eg: You have a Full on Sunday, an Incremental on Tuesday, and an Incremental on Wednesday all residing on Extent A. If on Thursday Extent A goes offline, without that option enabled, no backups will be created and the backup will fail. If that option is enabled, you will get a new Full backup on Extent B on Thursday, starting a new backup chain and continuing the backup chain on Extent B.

If you want to avoid any VMs with existing backup chains landing on Extent A from ever having a backup chain on Extent B, you need to uncheck both options and never run a new Active Full backup since an Active Full backup will go through the SOBR placement algorithm or simply do not use SOBRs, since one of the biggest benefits of SOBRs is to provide some intelligence around handling offline or full extents.

[edison5000]

Understood. Thanks Tyler. I also spoke to another tech about this. In my ideal universe, perhaps, there would be some identifier in B&R that clarifies the effect of the 2nd option if you have already checked the checkbox for the first one. Maybe a tooltip. : )