Forum Discussion

Symen's avatar
Symen
Level 2
11 years ago

Is it possible to create a VxVM Cascaded Space-Optimized snapshot from a Netbackup policy?

Hi, I'm trying to figure out if it is possible to create a VxVM Cascaded Space-Optimized snapshot from a Netbackup policy. The Snapshot client documentation indicates that it's possible to trigger ...
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  • RLeon's avatar
    RLeon
    11 years ago

    For VxVM based snapshot methods, regardless of whether it is for NetBackup's Instant Recovery feature, or for the more traditional backup-from-the-snapshot purpose, the snapshots that NetBackup instructs VxVM to create are always "independent" snapshots. That is, the snapshots are not dependent on their neightbouring siblings, but only to the orignal volume. (Or even not, if using full-sized instead of space-optimized snapshots.)

    The snapshots created by VxVM's Cascaded Snapshot feature, as well as the Snapshot of a Snapshot feature, are not independent snapshots; they depend on each other. And as documented in the Nbu snapshot guide, NetBackup does not create this type of snapshots through VxVM.

    Side note:
    One would argue that VxVM's Cascaded Snapshots - most likely redirect-on-write instead of copy-on-write based - is also a type of "Snapshot of a Snapshot" feature. But, alas, "Snapshot of a Snapshot" is already used to refer to something else specific.

RLeon's avatar
RLeon
Level 6
11 years ago

For VxVM based snapshot methods, regardless of whether it is for NetBackup's Instant Recovery feature, or for the more traditional backup-from-the-snapshot purpose, the snapshots that NetBackup instructs VxVM to create are always "independent" snapshots. That is, the snapshots are not dependent on their neightbouring siblings, but only to the orignal volume. (Or even not, if using full-sized instead of space-optimized snapshots.)

The snapshots created by VxVM's Cascaded Snapshot feature, as well as the Snapshot of a Snapshot feature, are not independent snapshots; they depend on each other. And as documented in the Nbu snapshot guide, NetBackup does not create this type of snapshots through VxVM.

Side note:
One would argue that VxVM's Cascaded Snapshots - most likely redirect-on-write instead of copy-on-write based - is also a type of "Snapshot of a Snapshot" feature. But, alas, "Snapshot of a Snapshot" is already used to refer to something else specific.