We are looking for Old Shuck’s SAN node performance figures, that is the speed over our 4Gb fiber link to BlackDog, our DAS node. These numbers should be much better than those of a comparable native drive, let alone our initial NAS speeds. Figure 19 shows our test topology.
Figure 19: DAS to SAN Test Topology
When initially started testing our SAN performance using Intel’s NASPT test suite, we got some outrageous numbers, like 2010 MB/s for the ‘File Copy from NAS’ test, and 1633 MB/s for ‘4x HD playback’. These indicated something was wrong or that we had inadvertently overclocked our PCIe x4 slot by a factor of two. Since there wasn’t any smoke pouring out of BlackDog, we guessed something was wrong.
After some brief research, we realized that we were boneheads, NASPT recommends a maximum of 2 GB of memory, being a Java application it uses the JVM for memory management. At 8 GB, caching was giving us speeds that were not in the realm of possibility (as much as we wanted to believe them…)
When we stripped back BlackDog down to 2 GB and retested, results emerged that made more sense (Figure 20).
Figure 20: Old Shuck SAN Performance
Very sweet numbers, with two exceptions, the Content Creation figure of 13.7 MB/s, which was most likely due to our stripe size, and the File Copy to Old Shuck, at 65.4 MB/s, still mysteriously low. Hopefully our planned tuning of BlackDog/Old Shuck as a logical NAS, in the next part, would give us a clue why this number was so much lower than our commercial competitors. It has us scratching our heads…
In Figure 21, we can see how we measure up against the SNB top performers. In all but the anomalous File Copy to NAS category, we trounce ‘em. But that is not a surprise, we’ve unfettered the traffic from the constraints of our Gigabit network.
Figure 21: Performance Comparison
Interestingly, if we compare the test figures of our SAN against those of the same kind of hard disk (compressed) connected on BlackDog’s SATA bus, Old Shuck still shines – putting CPU and fiber muscle behind the same model of disk makes a big difference (figure 22).
Figure 22: Hard Drive plus Standings
Though the conversion / configuration process is a bit complex, it is straightforward and took about 30 minutes, the most difficult part is making sure the scst configuration file is correct.
And as you can see by the benchmarks, the performance is outstanding.
Let’s say you make your HTPC the DAS server, running a long fiber cable from your living room (the WAF factor for the Norco case is right up there with the dogs playing poker painting), converting the NAS you built to a SAN for less than $300. Now you are able to stream the densest Blu-Ray resolution known to man directly to your TV without a hitch, dramatically reduce the time it takes to rip that same Blu-Ray disk - and store, if fully loaded, about fifty more terabytes beyond that. Do backups and update music and pictures from any machine in the house via that shared drive.
You won’t have to worry about performance or storage for quite some time (or until 2015, when storage guru Tom Coughlin comes knocking at your door with his Petabyte.)
In figuring out how to convert our NAS to a SAN, I’d be remiss in not thanking the sources used in solving a problem of configuring fibre channel, a problem that has no official documentation. First there is Snick’s thread in the Openfiler forums. The other source we used was Brian’s How To. Without their generosity I’d probably be bald, and launching expensive equipment through windows (the kind you see through walls with).