Support from Plextor is mediocre at best. Their support website is really devoid of anything useful, including not being able to download things like the manual. They don't even list their corporate address! Forget about re-downloading copies of Genie Backup too, as no software is available. Contacting technical support is via a phone number or live chat, found on the support website.
Figure 6: The only mention of the support phone number is on their RMA section of their website.
Live chat and phone support are available Monday through Friday, 9 AM to 6 PM PST. Tech support's phone number is not listed on the main Support page. I had to dig to find it listed on the "RMA" page (Figure 6) and it's also listed on the Contact Us page.
There is also a fairly useless FAQ and a user forum that looks more like a suggestion box, and does not seem very active at all. Finally, an email address of firstname.lastname@example.org is available to email in a question, although I imagine it's also staffed only during normal business hours.
Testing and analysis by Tim Higgins
The PX-NAS4's benchmark results are summarized in Figure 7. RAID 5 large file copy performance measured around 30 MB/s for write and 45 - 50 MB/s for read, depending on benchmark method. Performance as an iSCSI target with a RAID 5 based volume came in at 30 MB/s write and 39 MB/s read.
Figure 7: Plextor PX-NAS4 Benchmark summary
I was not able to run a network backup test to an rsync target, but was able to back up to a FAT formatted USB drive at a 14 MB/s rate.
Basically, the PX-NAS4's performance is more in line with older Marvell Kirkwood based products like the Buffalo TeraStation ES than with 1.8 GHz Kirkwood and Intel Atom-based NASes. Consult the New To the Charts article for more details of the PX-NAS4's performance.
Plextor has its work cut out for it if they are going to gain any serious market share. While it is a less-expensive NAS, for not much more money you can step into a NETGEAR, Synology, QNAP or other NAS that will outgun and outperform the Plextor.
Although the PX-NAS4 has some unique backup and volume configuration features, its odd quirks and outdated interface really limit it to consumer use, even though it contains several features that a home user would never access. Plextor also really needs to improve its support website and resources if they plan to be a serious player in the business NAS market.
A competitive comparison is best done using the Price versus Performance NAS charts. Filtered for four-bay products and using a RAID 5 File copy benchmark, the closest product is a Promise SmartStor 4600, an older product with limited appeal.
You basically want products to move higher up on the chart (Performance axis), but not farther to the right (Price axis). In this regard, the next closest product is the QNAP SS-439 Pro. Although it's $100 more expensive, the QNAP provides significantly more features, a better admin interface, and higher performance.
It does however only accept 2.5" drives, which limits storage space. I would probably still go this route though, since 2.5" drives are continuously reaching higher storage capacities and are much quieter and more power efficient for similar performance.