topic SnapVault, 2020, Dedupe, Long Term Retention in ONTAP Discussions

SnapVault, 2020, Dedupe, Long Term Retention

davieb1969 — Thu, 05 Jun 2025 06:51:32 GMT

Hi, I have a customer that will be using SnapVault to archive their data. This includes files data, Exchange, SQL and VMware.

They have the following requirements:

Data should be recoverable from any hourly snapshot going back 48 hours.
Data should be recoverable from any end of day point for the past 7 days.
Data should be recoverable from any Week end Point (23:00 Sunday) for the 5 past weekends.
Data should be recoverable from any Month end Point (23:00 Last calendar day of the month) going back up to 7 years (84 month end points)

What concerns me is the 7 year retention period. With a 2020 the maximum volume size when using dedupe is 1TB. I would imagine the data of each dataset is likely to go over 1TB.

What would you suggest? Do I not enable dedupe on the secondary?

Thanks

SnapVault, 2020, Dedupe, Long Term Retention

radek_kubka — Thu, 30 Jun 2011 11:30:00 GMT

7 years is almost infinity in the modern technology world

Just explain the limitations to the customer & consider using external shelves, only which hopefully one day may be attached to a bigger filer with bigger limits (yeah, I know DS14 shelves are already old...)

Or consider 2040 from the start with all the goodies of ONTAP 8, SAS-connected shelves, etc.

Regards,

Radek

SnapVault, 2020, Dedupe, Long Term Retention

davieb1969 — Thu, 30 Jun 2011 11:34:21 GMT

Hey Radek, hope you're well.

Unfortunately we are providing services through a third party and they have already supplied a 2020 and not told them about the 1TB limitation, but promised dedupe doh! So I'm stuck between a rock and a hard place.

I guess I will just have to leave dedupe off on the secondary filer, unless someone has a better idea.

SnapVault, 2020, Dedupe, Long Term Retention

radek_kubka — Thu, 30 Jun 2011 11:42:03 GMT

The question is how much data do they actually have / expect to have per volume?

If we are talking tiny amounts, 1TB still may be plenty, even after 7 years

Another unknown is dedupe ratio, as the volume might be capped at 1TB, yet effectively it can store more actual data.

SnapVault, 2020, Dedupe, Long Term Retention

davieb1969 — Thu, 30 Jun 2011 11:44:07 GMT

Indeed, but unfortunately I don't have this information. I'll have to play it by ear

SnapVault, 2020, Dedupe, Long Term Retention

sowens — Thu, 30 Jun 2011 16:23:26 GMT

The required retention policy of

48 Hourly

7 Daily

5 Weekly

84 Monthly

If we assume, a modest, 1% hourly, 2% daily, 3% weekly, 5% monthly growth, for a sample data set of 200 GB in the active file system, the amount of space for snapshots for the desired retention policywould exceed 800GB, which would put you beyond the 1TB dedup limit of the FAS2020