Adaptec’s Snap Server 730i device joins a rapidly growing number of similar appliances, including the Dell MD3000i that I tested in September.
While the details of these appliances differ, they all are designed to provide a storage destination for Windows and Linux servers, and can support attachments from multiple hosts at the same time.
One common feature is that these appliances make use of Microsoft’s iSCSI Software Initiator, a middleware package that lets Windows Server treat network-connected storage as if it were physically attached. All these appliances also require a driver set that controls the interface between the iSCSI initiator and the appliance.
These appliances include a storage management application—in the case of the Snap Server 700 series devices, the Adaptec Storage Manager—that lets users control configuration and operation. Adaptec Storage Manager provides access to the wizards that help make setup and management tasks something other than mind-numbingly tedious. (But that doesn’t mean you’d pick this management application as entertainment on a Saturday night.)
Adaptec’s Snap Server 700i series servers are 1U (1.75-inch) appliances that are designed to work on a Gigabit Ethernet network. The 730i that I tested includes dual redundant power supplies, four Ethernet ports and four SATA (Serial ATA) disk drives that can be set up as RAID 0, RAID 1 or RAID 5. Three of the Ethernet ports are designated for iSCSI traffic only. The first port (ETH0) is designed to support the management application and can also be used for iSCSI. The unit sells for $15,595 in the tested configuration.
The appliance I tested included four 750GB SATA drives. One was assigned as a hot spare, and with parity space, and the other three provided about a terabyte and a half of usable storage space. I created two partitions using the available space, but I could have partitioned as many as 512 volumes.
While the 700i series appliances are limited to four internal disk drives, a 2U (3.5-inch) chassis can be added that bumps the storage up to 33TB. The device will support either SATA II or SAS drives. This translates into 44 SATA drives or 96 SAS drives, for a total of 28.8TB. All these are hot-swap drives, and they include a fault indicator that makes it easy to find and replace a tanked drive.
If a drive does fail, the appliances bring the hot spare online at once. Then, when the failed drive is replaced, it becomes the hot spare. The Adaptec driver software also keeps an eye on the Ethernet connections and does an automatic fail-over if one of the Ethernet ports fails.
Once I got past the initial setup and installation of the Snap Server 730i, there really wasn’t much involved with using it. The device looks like any other storage target to a server. In the case of Windows Server, it appears to be an attached disk drive. What’s nice about the Adaptec product is that getting to that state is fairly painless.
Adaptec has instilled its Storage Manager with a series of wizards that let me get a basic iSCSI SAN (storage-area network) up and running quickly and easily. I set up the IP addresses on each Ethernet port first. The Snap Server 730i will work with DHCP (Dynamic Host Configuration Protocol), but Adaptec recommends it. There is good reason for this, as you don’t want your SAN changing IP addresses when you don’t expect it, but the company doesn’t explain why DHCP is even an option on the 730i.
When running the setup wizard, drivers are installed so that the server operating system can see the SAN. This, in turn, lets the iSCSI initiator communicate with the SAN. When I installed the Adaptec software on an HP DL385 server, both Ethernet ports on the server were enabled, but the storage software was able to use only one of them. This meant that all storage traffic was funneled through a single network port, limiting performance.
During the course of testing, Adaptec provided a version of its driver that would let the iSCSI initiator load-balance between both Ethernet ports. This did improve performance, but it’s unclear whether the company is making a version with these settings generally available.
Once they were done running, the Adaptec Storage Manager wizards delivered an operational SAN. You will likely need to tweak the default settings to meet your specific needs, but some of this can be done during initial setup if you know what the settings will be at that time.
Unfortunately, the Adaptec Storage Manager has an inconvenient issue of its own. When installed on a Windows XP-based management console, the app sometimes loses sight of the SAN. The only way to regain a connection so you can manage the Snap 730i is to restart the computer that has the Storage Manager running on it. According to the company, this problem happens intermittently with XP and Vista clients, but not if the app is installed on Windows 2003 Server. The problem is being worked on, according to a company spokesperson.
Beyond the inconvenience of having to restart it from time to time, Adaptec Storage Manager is easy to use and it makes visualizing the state of your storage—even if it’s a lot of storage—easy to accomplish.
There is one problem the 730i shares with all other iSCSI appliances that are based on Gigabit Ethernet: The performance of the storage device is overshadowed by the performance of the network –or, perhaps, the lack of performance. With the Snap Server 730i, for example, four Gigabit Ethernet ports are available, one of which is a shared port with at least some resources going to management. The best you’re going to be able to do with this device is 4 gigabits, and that assumes that your server, the intervening infrastructure and the 730i itself all are working at peak efficiency.
I used a D-Link DSG-3627 Gigabit Ethernet switch during my tests. Performance with this switch and the Snap Server 730i was basically the same as the previous test with the Dell MD3000i, despite the Dell’s greater number of faster disk drives. The reason, of course, is that the speed is limited by the network infrastructure to a gigabit per port.
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