NAS Revisited: More On ReadyNAS

Continued from 'NAS Revisited: The Infrant Alternative'….

All and all, I found the ReadyNAS X6 to be a solid and full-featured product. Make sure you peruse the other reviews I provided links to at the beginning of this writeup; I concur with pretty much all of the praise that my counterparts heaped on Infrant and its product. With that said, I encountered a few glitches that bear highlighting. First off, I guess I'm spoiled, because I naturally assume nowadays that any LAN-connected piece of equipment is DHCP-enabled from the get-go and is also configurable via a web browser. I was surprised, therefore, to discover that the documentation directed me to install and run a Windows-only (too bad, so sad, Linux and Mac users) setup utility.

The utility found the ReadyNAS and, surprise again, promptly launched my Firefox browser into a secure HTTP login page (https://INSERT_READYNAS_IP_ADDRESS/admin). Sigh. While I understand that the act of perusing a router's DHCP logs to discover the address a new LAN peripheral has grabbed may be beyond the average user, there should at least be an appendix for folks who want (or need, in the case of non-Windows operating systems) to bypass the interim LAN interrogation utility step. I also got two spurious certificate warning pop-ups (chronologically ordered screenshots are here and here) each time I visited the ReadyNAS configuration pages; I knew enough to ignore them, but a typical consumer would likely be apprehensive, prompting an expensive technical support call.

Due to an apparent hardware defect with my ReadyNAS, the supposed 'graceful' power-off using the front panel toggle button resulted in a 15-minute error-checking sequence each time I subsequently powered the unit back on. If I powered off the unit via the web browser interface, subsequent power-up was rapid and normal, as expected. Infrant was able to replicate this problem (although I haven't yet heard back on a root cause); I haven't yet tried out the replacement unit they provided me. However, this was an ideal opportunity to test out the ReadyNAS's built-in error email-outputting SMTP server, which worked like a charm and neatly circumvented the lack of port and secure server authorization that had prevented me from using this feature on the TeraStation.

Now to what you're all really waiting for; performance tests. First, though, remember that although my LAN's Gigabit switch is Jumbo Frame-capable (as is the ReadyNAS), none of my Macs' or PCs' Gigabit Ethernet controllers supports Jumbo Frames. So, the performance data I've logged is (potentially) not best-case. What I've done so far, as with the TeraStation, is my 'torture test'; moving and then moving back a 6.8 GByte file as fast as possible using my Dell PowerEdge 400SC. Here, too, a qualifier is in order; rarely (except, perhaps, when doing a HDD-to-NAS backup, or a reverse-direction restore) does an application transfer such a large amount of information in an as-fast-as-possible manner. More common is to move or copy a much smaller file, or to stream data at a slower speed (such as when archiving or playing back standard or high definition video).

With these 'but's out of the way, let's first look at the speed I obtained when writing the file to the ReadyNAS. Here's the screenshot. Now compare it to the screenshot I earlier obtained when writing the same file to the TeraStation. You should notice two things in the ReadyNAS case:

• Higher peak bandwidth (I measured 80 Mbps), and
• No frequent, dramatic transfer lulls (which again, in the TeraStation case, I attributed to the PowerPC having to periodically do XOR parity calculations, calculations which the ReadyNAS hardware XOR circuitry can more rapidly complete)

However, the ReadyNAS write transfer speed still does slightly oscillate, and occasionally it exhibits more dramatic, albeit brief, slowdowns.

What about reads? Here's where things get real interesting. First, here's the ReadyNAS screenshot. Next, since I didn't earlier provide it, here's that same file being read from the TeraStation. The ReadyNAS starts out great, at a sustained ~190 Mbps read speed. However, less than 20% through the transfer (at a bit over 1 GByte of data read) the speed drops down to 90 Mbps, with periodic dips to roughly half that rate. The TeraStation, conversely, achieves a pretty consistent 90+ Mbps transfer rate throughout the whole cycle.

I suspected that the initial ReadyNAS 190 Mbps read transfer speed was a function of data streaming out of the HDD RAM buffers (after all, I'd written to the HDDs immediately before reading back from them) and that once the buffers were starved, the slower transfer rate reflected reading data directly off the drives' rotating magnetic media. That interpretation would, among other things, correlate to the TeraStation HDDs' slower PATA interface and smaller 2 MByte buffers. I asked Sam to have his engineers analyze my data, to confirm or refute my hunch. Here's what he came back with:

Continued with 'NAS Revisited: The ReadyNAS Remainder'….