Just a few years ago the cost per gigabyte and the expertise necessary to implement a storage area network (SAN) exceeded the resources of midsize businesses. That has changed thanks to SATA, iSCSI and the setup software some vendors have for their hardware. Today, you can get a terabyte of storage for less than US$10,000.
One product is the Dell/EMC AX100, an entry-level SAN kit combining SATA drives, an Fibre Channel (FC) switch, HBAs, a UPS, cabling and smooth setup and management software from EMC.
Now comes the AX100i, a low-end iSCSI SAN. The AX100i is identical to the original AX100 with the exception of the iSCSI ports on the service processors (SPs). With a top-end capacity of 3TB, the AX100i can scale to suit any small-business application.
As with the original AX100, the target of the AX100i is the SAN novice. When the array arrived from Dell, I was able to configure and deploy it to a Linux and Windows server within one hour.
Defining arrays and virtual disks is straightforward. You select the physical disks from a representative layout grid, define the array parameters, such as stripe size, and you’re done. You can then create virtual disks of variable sizes and bind them to specific hosts for proper presentation. You can just as easily expand virtual disks.
I did run into a problem. When the test unit first powered up, the second SP was unavailable for configuration. Although the SP was pingable, I could not change the IP and subnet assigned to its iSCSI port. After I stepped through the remediation procedure provided by Dell, this SP simply would not perform properly, except with a host attached. When Dell sent another unit, the new one initially exhibited the same behaviour, but resetting it solved the problem.
On the Windows side, mounting SAN volumes on a server with redundant paths to the array requires EMC’s PowerPath. This is standard operating procedure, and presented no surprises. The Windows server accepted a single path to the SAN, and PowerPath held down the redundant path as expected. The AX100i can support eight servers with redundant paths, for a total of 16 connections. You can easily implement snapshot features for quick data recovery.
Unfortunately, the ease of installation and configuration of the AX100i comes at a price. Features you would expect to see in any iSCSI SAN solution, such as jumbo frame support and flowcontrol settings on iSCSI ports, are MIA.
Today, the AX100i delivers a level of performance comparable to many simple NAS devices, but nothing close to a well-implemented SAN. For applications requiring consistently fast access to volumes, though, you should look elsewhere.