ZFS Replication missed snapshot

[djb]

Hello everyone with a question:

What will happent if the target machine is turned off at the time of replication ?
What will happent if the source machine in the meantime create the next snapshot ?
What will happent when the target machine boots up and missed ZFS Replications of previous snapshots ?

Thanks for any comments.

 

[Samuel Tai]

All the interim snapshots will replicate at the next replication interval time when the target and source are both online, and whatever snapshot lifetime you have for the snapshot task will automatically remove snapshots older than the expiration lifetime.

 

[djb]

Thank you Mr Samuel.
So what will be your suggestion for remote off-site backup using ZFS replication for a storage system ?
For this task i don't really need snapshots to revert back, this happent on the main system with 5 minute interval. So lifetime of snapshots can be 5 days, and maybe replicate once a day ? What do you say?

 

[Samuel Tai]

Without knowing your business needs, and the size of the link between your primary and backup sites, I can't say whether your proposed replication interval will work for you. Note, snapshots every 5 minutes means 1,440 snapshots per day. Is your link large enough to handle this?

 

[djb]

Without knowing your business needs, and the size of the link between your primary and backup sites, I can't say whether your proposed replication interval will work for you. Note, snapshots every 5 minutes means 1,440 snapshots per day. Is your link large enough to handle this?

yes, the incoming data every day is under 100MB.
the 5 minute snapshots are expired in an hour. This is for users that messed up with files in SMB.
Then snapshots every 1 hour with retention of 1 day for systems and VM's.
So the next step i see is 1 snapshot for ZFS Replication daily and lifetime 5 days.

 

[guermantes]

@djb
Since you asked above about what happens when a machine is turned off, let me direct your attention to the fact that if your snapshot lifetime is five days you cannot leave a computer off for more then four days (perhaps five, but four to be sure ) because then, if it is the destination you turn off, the last snap on the destination would no longer exist on the source machine when you boot up the destination and the incremental replication would break down. But perhaps you are not doing incremental?