SAN to SAN replication queries for DR

1) If for your DR/backup you initially write backups to your primary SAN, and then there is a hardware level replication between your primary SAN and DR SAN, therefore the same backup files are on 2 SAN's in differing offices, would this classify as 2 copies of backups. I know for critical systems best practice states have 3 copies, would this class as 2?

2) also - what kinds of issue/risk/incident could take out both your primary SAN and DR SAN, therefore leaving you without live copies of data and backups? our technical team say their DR setup is sufficient, but from our risk angle we want to have some view of risks and probability to see if a 3rd backup is required?

3) And also - given the setup I have described, what options could there be for implementing a 3rd copy of the backup, e.g. tape backup attached to the DR SAN and taken offsite?? The budget is limited so need to determine if a 3rd backup is necessary and what options could be used, and some idea for each option which are the less expensive and which are the more expensive?

4) Is 'primary SAN' the correct terminology to describe your SAN in your main data centre? And is 'DR SAN' the correct terminology to describe the SAN at your DR site?
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pma111Asked:
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
1) If for your DR/backup you initially write backups to your primary SAN, and then there is a hardware level replication between your primary SAN and DR SAN, therefore the same backup files are on 2 SAN's in differing offices, would this classify as 2 copies of backups. I know for critical systems best practice states have 3 copies, would this class as 2?

Yes, but to be honest with you, why would you put backups on the same SAN as Production ? if the SAN fails all your backups have gone.

2) also - what kinds of issue/risk/incident could take out both your primary SAN and DR SAN, therefore leaving you without live copies of data and backups? our technical team say this is sufficient, but from our risk angle we want to have some view of risks and probability to see if a 3rd backup is required?

Corruption.

In our opinion, backups should be in 3 places! A backup is not a backup unless in three places!

3) And also - given the setup I have described, what options could there be for implementing a 3rd copy of the backup, e.g. tape backup attached to the DR SAN and taken offsite?? The budget is limited so need to determine if a 3rd backup is necessary and what options could be used, and some idea for each option which are the less expensive and which are the more expensive?

Tape, Disk as Tape, or Cloud

4) Is 'primary SAN' the correct terminology to describe your SAN in your main data centre? And is 'DR SAN' the correct terminology to describe the SAN at your DR site?

No we have many types of storage NAS, and we also have near line archive, and offline archive, so ALL data which has not been access for a particular amount of time, set by policy is "moved" to tape very quickly, and when someone wants it back, it's very quickly pulled back of tape!

But to the end user, it's always available.... (but to Admin staff it's not on live storage wasting space)
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Dr Christophe TrefoisResearcher / IT SpecialistCommented:
1) I would say not really, because if your primary gets deleted / corrupted, your DR will be as well.

To me it is like asking if database replication can be considered as a backup, for which the answer is clearly no.
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