Virtual Libraries/Drives/Cartridge Configuration - HP StorageWorks 12000 - Virtual Library System EVA Gateway Manual

VLS model
VLS9000–series
VLS12000–series

Virtual Libraries/drives/cartridge Configuration

The VLS provides a very flexible virtual library configuration, allowing you to create many more virtual
tapes drives than a physical library could contain (and therefore run many more concurrent backup
jobs), and to create virtual cartridges of any required size. On the multi-node devices such as VLS9000
and VLS12000, you also have the key ability to create a virtual library across the VLS nodes (see
Scalability) thus providing a single backup target with the entire device performance and capacity if
required along with the ability to increase the virtual library performance by adding more nodes at
a later date.
When designing the virtual library configuration keep in mind the following considerations:
• The virtual library emulation type can be whatever is certified on the backup application. For ex-
ample, Symantec NetBackup certification requires an emulation that is not the same as a physical
library so the "HP VLS" library type is used for this. For other backup applications any library
emulation can be used but generally the "HP ESL-E" is the most flexible emulation because it can
scale to 10000 slots and 1024 drives (the same as the HP VLS emulation). Remember that the
virtual library does not in any way have to match any existing physical library because it is a
brand new library on the SAN. It will have very different geometry because it will have many
more drives and slots than the physical library and will also have different SAN WWPNs and
serial numbers (i.e., it is not a replacement for the physical library).
• You always need to have multiple concurrent backups going to the VLS to achieve maximum
throughput. Therefore, analyze how many concurrent backup jobs will be needed to saturate the
VLS performance and create at least that many virtual tape drives in the virtual library. Do not
create more drives than you need because there is a minor performance impact (e.g., 5-10%) if
you use the maximum number of drives per node compared to the optimum performance at 4-8
drives per Fibre Channel port.
• Load balance your virtual devices across the ports. For example, if you have a four-port configur-
ation and you configure a 24-drive library, you should spread the drives evenly across the ports.
Ensure that your backup application also balances the drive distribution.
• With VLS9000 and VLS12000, you can upgrade capacity as needed after the initial setup. To
prepare for future expansion, the user should configure additional drive bays and slots on the
virtual robot to avoid having to delete and recreate the virtual library when expanding capacity.
• If you initially deploy without deduplication (with a maximum virtual drives per node of 128) but
you intend to enable deduplication in the future, limit the maximum number of virtual tape drives
per node to the deduplication limit which is 96 virtual devices (robots and libraries) per node.
This will then make the migration to deduplication easier.
• If possible, configure eight or fewer LUNs (virtual devices, including the robot) per port. Some
operating systems will not see more than this. If you need more than eight devices on a port, you
must use LUN mapping and masking.
• HP recommends that you do not delete individual tape drives from inside the virtual library. Deleting
drives in the virtual library introduces gaps in the LUN numbering for shared (unmapped) virtual
tape drives, and many operating systems fail to scan the virtual tape drives that follow a gap. In
multi-node configurations, it can change drive element addresses. In both cases, when the device
reboots it will reorder the LUNs/elements of the tape drives and may require reconfiguration of
the media server tape paths.
118 Virtual Library Systems
Capacity upgrade license
Enables an additional 30 or 40 TB VLS9000 array per license.
Enables an additional 2 TB (1 LUN) per license.
VLS