ZxPowerstore: Hierarchical Storage Management
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The Hierarchical Storage Management technique
HSM is a data storage technique that moves data between different stores according to a defined policy.
The most common use of such technique is the move of "older" data from a faster-but-expensive storage device to a slower-but-cheaper one on the following premises:
- Fast storage costs more.
- Slow storage costs less.
- "Old" data will be accessed much less frequently than "new" data.
Thus said, the advantages of the HSM technique are clear: Lowering the overall storage cost, since only a small part of your data needs to be on a costly storage, improving the overall user experience.
Stores, Volumes and Policies
Dealing with the HSM technicque requires a clear understanding of some related terms:
- Store: a generic term to describe a place where data is stored.
- Primary Store: The "fast-but-expensive" store where all your data is initially placed
- Secondary Store: The "slow-but-cheap" store where "older" data will be moved
- Volume: the physical representation of the notion of Store. A volume is a distinct entity (path) on a filesystem with all the associated properties.
- Policy: A rule that determines what data will be moved between the volumes.
ZxPowerstore: HSM for Zimbra - the ZeXtras way
The ZxPowerstore module allows you to use the HSM technique on your Zimbra Open Source Edition server.
With the ZxPowerstore module you can:
- Create, edit and delete Zimbra volumes
- Change the active primary volume of your Zimbra server
- Define advanced policies
- Apply your policies manually or through an integrated scheduling system
All of this operations can be done both through the ZeXtras Administration Zimlet and the ZeXtras CLI.
Running ZxPowerstore on Zimbra Network Edition
Unlike the Open Source Edition, Zimbra Network Edition includes its own HSM system.
While Zimbra's HSM and the ZxPowerstore are not incompatible per-se, there are some basic measures to be observed in order to avoid the two components to "step on each other's feet":
- Zimbra's HSM and ZxPowerstore share the same policy, so you won't be able to configure different policies for the two components.
- Don't run Zimbra's own `zmhsm` command, either manually or through scheduling, when ZxPowerstore's `doMoveBlobs` operation is running.
- Zimbra's HSM and ZxPowerstore share the same volumes and "current" settings, so you won't be able to apply the same policy to different stores by running the two components one after the other.
To enable ZeXtras Powerstore on Zimbra NE run:
zxsuite powerstore setProperty ZxPowerstore_EnableHsmOnNe true