Configuring Storage Pools

With Pools, physical disks and vcartridges can be configured to belong to a specific pool. For example there can be a SSD pool and all SSD disks can be configured for this pool. Vcartridges created can be then be configured to use this pool and any data corresponding to the vcartridge will be written to any available SSD disk within the SSD pool.

Creating a new Storage Pool

1. Click on "Storage Pools" menu

2. Click on the "Add Pool" button.

A form is displayed as shown in the figure below

Add Storage Pool Form

3. In the "Add Storage Pool" form shown enter the name of the pool to be created

4. Select "Enable Dedupe Metadata" if this pool needs to maintain its own metadata (described further below)

5. Select "Enable Deduplication" to enable data deduplication for vcartridges in the pool

6. Select "Auto-Export" if data in a vcartridge needs to be exported to a corresponding physical tape on export from the VTL

7. Select "Auto-Replication" if data in a vcartridge needs to be replicated to a corresponding virtual tape on another VTL.. Auto-replication will be performed when a vcartridge is moved to an Import/Export port by the backup software or when a vcartrridge is unmounted from a drive. If auto-replication is selected, hours during which auto-replication is allowed can be specifed using "Start Time" and "End Time" in a 24hr format HH:MM. If "Start Time" is equal to "End Time". If "Start Time" is equal to "End Time" then there is no restriction on the auto-replication schedule.

8. Specify a threshold percentage between 1 and 99 to for automatic caching and deletiong of exported virtual cartridges. When the available space in a storage pool falls below this threshold percentage, any exported or replicated vcartridge will be deleted to reclaim back space used by that vcartridge. A value of 0 indicates that virtual tape caching polices will not be applied to this pool.

9. Select "WORM" if all vcartridges from this pool need to have the WORM property enabled

Except for the WORM option all other options are only available with the extended edition product

10. Click on submit

Once a pool is created, to add a disk or a vcartridge to this pool, select the pool when adding the disk or creating a vcartridge.

"Default" pool

The Default pool is a system defined pool and cannot be deleted. The Default pool is special in that a disk configured for the default pool can hold deduplication tables for other pools and also log data for other pools.

Enabling deduplication metadata for a pool

Deduplication tables are written to disk. Each pool (including the default) would have a master disk. The master disk is the first disk configured for that pool. A pool can maintain deduplication tables and log information on its own master disk or on the master disk of the "Default" pool. If "Enable Dedupe Metadata" is selected when creating a pool, the pool will maintain its own deduplication tables else the master disk from the "Default" pool is used. If a pool depends on the Default pool for either data deduplication tables or log information then atleast one disk needs to be configured for the Default pool.

Memory available in the system play a major role in the number of pools that can maintain their own deduplication tables. In general for every 2GB of memory available, 2 pools can maintain their own deduplication tables

Impact of Pools on deduplication

Pools have a significant impact on deduplication ratio. For example, lets assume two vcartridges 'V1' and 'V2' are configured in the system. VCartridge 'V1' however belongs to Pool 'A' and VCartridge 'V2' belongs to Pool 'B'. Even if VCartridge 'V1' receives data which is identical to that on VCartridge 'V2', the data cannot be deduplicated as 'V1' and 'V2' belong to different pools.

Listing currently configured pools

The currently configured pools can be view by clicking on the "Storage Pools" menu.

The "Disks" column indicates the number of physical disks configured for the Pool.

Click on the "View" link to change a pool name, list the physical disks for configured for a pool and also the pool disk usage statistics

Default Pool Configuration

To change the default pool name add the following line to /quadstorvtl/etc/quadstor.conf (create it if required)

DefaultPool=<new name>
For example:
DefaultPool=NewPool

To enable Auto-Export for the default pool add the following line to /quadstorvtl/etc/quadstor.conf

DefaultPoolAutoExport=1

To enable Auto-Replication for the default pool add the following line to /quadstorvtl/etc/quadstor.conf

DefaultPoolAutoReplicate=1

To specify a threshold for the default pool add the following line to /quadtorvtl/etc/quadstor.conf

DefaultPoolThreshold=<A value between 1 and 99>
For example:
DefaultPoolThreshold=10

To enable byte-per-byte comparision of possible duplicate blocks and the stored blocks for the default pool add the following line to /quadstorvtl/etc/quadstor.conf

DefaultPoolEnableVerify=1