With a list price of $65,500, three NSM 200 with 3.84TB capacity cost about $17 per gigabyte, which makes the DSM 4.2 solution from LeftHand Networks one of the most affordable SANs I have reviewed.
To create the IP network to review DSM, I used a Netgear DSM712 GbE (Gigabit Ethernet) switch, setting single connections for each server and dual links for each NSM. My hosts were an HP ProLiant ML350 and DL360 running Windows 2000 Advanced Server with SP 4 and Windows Server 2003.
To simulate a remote office for the test of Remote IP Copy, I slightly changed my DSM configuration, using SCC to remove one of the NSMs from my cluster and connect that unit plus one of the servers to a different switch. To simulate a WAN malfunction, I broke the switch-to-switch link during replication.
Running Iometer scripts on my servers, I created data traffic mimicking I/O intensive server load and large block transfer rates typical of backup applications.
I ran resilience and recovery tests by removing physical drives and cutting connections between switches and disk enclosures. In each case, I started an application on my server and removed one of the devices or components affected by I/O operations. Invariably, the application continued to run undisturbed, and the NSM recovered after reinserting the failed component. Running applications were unaffected by significant configuration changes, such as removing or adding an NSM to a cluster or changing the snapshot schedule.