Minimum retention time for immutable backups

[chaos]

Hi everyone,
we're redoing or backup SLAs with different tiers for our block based hardened v13 repos.
One question that came up, regarding our "cheapest" SLA is regarding immutability.

As I understand you have to account the the full chain:
minimum immutability: 7 days
minimum block regeneration: 10 days - this is only applicable for object store, isn't it?
backup chain: 1x full + 6x incr per week

does this mean I have 24 days (7 days (backup chain) + 7 days (immutability) + 10 days (block regeneration)) of retentions points?

[Mildur]

Hi chaos,

Block Generation applies only to object storage and can be ignored when estimating a Hardened Repository.

With a 24-day retention, choosing 7 or 24 days of immutability makes no practical difference; backup files remain on disk for the same total duration regardless of the immutability setting.
Keep in mind, that GFS restore points will be immutable for their entire period. If you configure Yearly GFS to 10 years, yearly GFS restore point will be immutable for 10 years.

Best,
Fabian

[chaos]

Thanks Fabian,
so the shortest possible timespan with immutability is - given daily backup with one full per week and 7 days immutability - 14 days, right?

[Mildur]

Yes. 7-14 days with regular weekly full backups.

Best,
Fabian