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Comment by thayne

3 years ago

It doesn't solve the problem that sending that snapshot to a backup location takes a long time.

4 comments

thayne

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dsr_  3 years ago

No, it doesn't.

It takes exactly the time that it takes, bottlenecked by:

* your disk read speed on one end and write speed on the other, modulo compression

* the network bandwidth between points A and B, modulo compression

* the size of the data you are sending

So, if you have a 10GB database that you send over a 10Gb/s link to the other side of the datacenter, it might be as little as 10 seconds. If you have a 10TB database that you send over a nominally 1GB/s link but actually there's a lot of congestion from other users, to a datacenter on the other side of the world, that might take a hundred hours or so.

rsync can help a lot here, or the ZFS differential snapshot send.

nightshift1  3 years ago

Unless your storage is already mirrored off-site. Ex: EMC srdf

  • thayne  3 years ago

    so say the disk fails on your main DB. or for some reason a customer needs data from 6 months ago, which is no longer in your local snapshots. In order to restore the data, you have to transfer the data for the full database back over.

    With multiple databases, you only have to transfer a single database, not all of your data.