LSI OnStor 3510 NAS Gateway

As storage area networks (SANs) grow to keep up with demand, they inevitably get split up into islands handling small groups of servers and providing resources for specific applications. SAN islands do have their benefits but the downsides are that data can’t be shared between them, management overheads are high and data backup and recovery processes are complex.

LSI’s OnStor appliances can amalgamate your SAN islands and direct attached arrays into a single, unified storage pool which are recognised by a computer as a NAS share. The OnStor 3510 NAS Gateway is a 1U appliance which has four 4Gbps FC and four Gigabit Ethernet ports, support for both CIFS and NFS shares and a range of other standard features include clustering, snapshots and storage provisioning.

Once your SAN islands are connected to the OnStor's FC ports, all their storage are presented as CIFS and NFS shares. There's support for popular FC switches including Brocade, Cisco and QLogic and you can direct attach FC arrays as well.

The OnStor appliance uses virtual servers to present shares. Each one combines a collection of LUNs (Logical Unit Numbers) on its FC storage ports, which are then assigned to the Gigabit data ports. Multiple appliances can be gathered together as clusters with SANs connected across them all so access to storage is maintained, even in the event of an appliance failure.

Linking remote SAN islands together isn’t so simple and will depend on the link speed between the various locations. OnStor appliances can be located at each site and joined together in a stretched cluster but they communicate via their management network ports and for this to work the link must have a latency of less than 5ms.

Installation starts with the OnStor’s well-designed web interface. This lets you not only manage the local appliance, but others as well simply by providing a suitable name and the IP address of the other appliance's management port. If you have multiple appliances, these can be placed in groups for clustering and failover.

Before creating virtual servers, a few prerequisites need to be performed to make this a smoother process. For access authentication it supports LDAP, NIS domains for NFS clients and Windows domains for CIFS clients. We had an AD server on our test network, so we needed to set up our domain credentials first.

You also need to decide how you want the Gigabit Ethernet ports to function. The physical ports are referred to as file ports and these can be configured as individual logical ports or grouped together. For the latter, you can choose an aggregation mode where the appliance performs load balancing across all group members or you can opt for failover mode to provide standby links.

For testing we connected an IBM System Storage DS5020 array and started by visiting its own management interface to carve up its storage, ready for presentation to the OnStor appliance as LUNs. We were able to quickly create hosts and storage mappings on the DS5020 as it automatically detected the OnStor’s FC WWNs (World Wide Names).

Once the mappings to the OnStor FC ports were completed, we saw them appear in its own web interface as new LUNs marked as foreign and free. Each one can then be assigned to an OnStor cluster and configured as a RAID array.

Once the LUN has been labelled, it is then free to be assigned to a virtual server. The creation wizard lets you name the new virtual server and assign a single file port or port group to it. This logical data port assignment option proved useful as it allowed us to direct host access to specific logical drives over one port to avoid any network bottlenecks during performance testing.