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By: Chris Blackwood

 

There’s nothing really sexy about tape technology.  In some ways I think it’s a bit like minivans.  Lots of folks have them, a few really like them, but most people probably wish they could get away with something else.  Fortunately for tape users there are practical alternatives that can help reduce the dependency on tape technology.  There are times when we talk to customers that wish to completely eliminate tape from their environment.  And there are times when tape remains in the landscape.  It really just depends on the requirements.  But I want to discuss a couple common “requirements” that typically result in the tape discussion.

 

Long term retention

Probably the most common requirement that results in tape discussions is that of long term retention.  Folks that have requirements to keep 5 or 6 or even 7 years of backups tend to think that tape is the only answer.  The fact is, we can keep years of backups on disk.  Here are a couple examples where long term retention is stored on secondary storage:

  1. Using roughly 245 snapshot copies we can create a scenario with Protection Manager where backups run every 6 hours.  Those 6-hour backups are retained for 1 day.  Daily backups are retained for 3 months.  Weekly backups are kept for 2 years, and monthly backups are kept for 7 years.

Hourly                   Every 6 hours with 1 day retention

Daily                      Every day with 3 month retention

Weekly                 Every week with 2 year retention

Monthly               Every month with 7 year retention

 

  1. Using roughly 247 snapshot copies we can create a scenario with Protection Manager where backups run every 6 hours.  Those 6-hour backups are retained for 1 day.  Daily backups are retained for 4 months.  Weekly backups are retained for 2 years, and monthly backups are retained for 5 years.

Hourly                   Every 6 hours with 1 day retention

Daily                      Every day with 4 month retention

Weekly                 Every week with 2 year retention

Monthly               Every month with 5 year retention

 

In the examples above Protection Manager would control the replication and retention while consuming less than 250 snapshot copies.  This leaves a few snapshot copies available for other use if needed.  One of the assumptions required for this to work is that all backup schedules (hourly, daily, weekly, and monthly) would need to occur at a common time of the day.  For example, in the chart below 10PM is common across all of the schedules (10PM wouldn’t need to be configured for hourly backups since it would be accomplished by the daily, weekly, or monthly schedule)…

 

 

Example   Schedule




Retention

Schedule

Frequency

Time

Hourly

Every 6 hours

4AM, 10AM, 4PM

24

Hours

Daily

Mon-Sun

10PM

90

Days

Weekly

Every Sunday

10PM

104

Weeks

Monthly

1st Sunday in Month

10PM

84

Months

 

 

Keep in mind that while these backups are represented as full backups (because of snapshot technology) they are achieved using block-level-incremental technology.  These scenarios are shown from the secondary storage perspective.  Other copies (typically with shorter retention) would also be available on the primary storage.  For most restores you would expect to simply recover data locally.  However, these long term backup are available on secondary storage for more dated recoverability.

 

Offsite requirements

Another reason people think about tape is because they have a need to ship backups offsite.  Sometimes it is mandated that backups be on magnetic tape.  But often this is not the case.  Backups performed using NetApp disk-to-disk solutions can take shape in a few ways.  First, backups can be done from one site to another.  This results in local recoverability plus longer term retention at the remote site.  Another approach would be to perform backups locally (within the production site) and mirror those backups to a remote site (see illustration).  This has the advantage of maintaining geographic proximity of the backups within the production site.  It also provides an additional copy of those longer term backups at the remote site.  Another advantage of this approach comes in the form of WAN efficiency.  Assuming the backup are deduplicated at the production site, those backups are mirrored in a deduplicated state to the remote site.  So tape can be a part of the environment if desired, but it doesn’t always need to be.

 

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