The ol' review queue has filled up with products, so the Fast NAS experimentation has moved to the back burner for a bit. But with a little prodding from the Forums crew, I decided to take a quick look to see what sort of performance that iSCSI can bring to the table.
iSCSI is a protocol that allows clients (initiators) to send SCSI commands to SCSI storage devices (targets) via a TCP/IP network connection. iSCSI's main use is to build Storage Area Networks (SAN) using Ethernet-based networks instead of dedicated connections such as Fiber Channel. iSCSI drives appear to an operating system as locally mounted drives.
An opportunity came in the form of the Sans Digital MN4L+B that I spent a much of this week testing. It's based on an Intel Pentium M and its performance runs neck and neck with the QNAP TS 509 Pro that reader Dennis Wood has been having so much fun with.
The MN4L+ (I'll dispense with the "B" since that just indicates the black case version) has both iSCSI initiator and target modes built in along with its high SMB/CIFS performance. So I decided to use the Windows iSCSI initiator to run some iozone tests on the MN4L+ as an iSCSI target.
Windows iSCSI Initiator
I started with Vista, since it has the initiator built right in. But I also ended up downloading and installing the initiator on the copy of XP that is dual-booted on the same machine, which I have been using as the Fast NAS test system. Keep in mind that this system has 512 MB of memory, which causes performance improvement due to caching to fall off sooner.
Figure 1 shows the Windows iSCSI Initiator Properties Control Panel. I didn't mess with changing the Node name, since you must follow a particular convention.
Figure 1: Windows iSCSI Initiator - General
I first made sure that iSCSI target support was enabled on the MN4L+ and that an iSCSI volume was created. I then moved to the Discovery tab (Figure 2) and entered the MN4L+'s IP address. I was a bit puzzled that there was no connection confirmation, so I wondered whether I had actually connected. But I later learned, when I tried to enter an IP address that did not have a valid target, that the Add Target Portal window just stays up and you eventually get an error message in that case.
Figure 2: Windows iSCSI Initiator - Discovery
Clicking on the Advanced button brings up the Advanced Settings window (Figure 3), which contains logon options, including settings for CHAP authentication for secured targets.
Figure 3: Windows iSCSI Initiator - Advanced Settings - General
The Advanced Settings - IPsec tab (Figure 4) allows the use of a secure IPsec tunnel secured with a Pre-shared Key for both authentication and data transfer for those targets that support it.