I would agree that for the most part a majority of the people using this device are not storing a massive collection of Outlook PST files and trying to access them from the device, and I do not think it is a huge deal that it isn't possible to do, as I like using EXT3 since I have windows and a MacBook that access data from the device so the trade off of not needing two NAS devices, one for my Mac and another for my windows boxes is worth it. BUT that said I do have a 500 Mb PST file that I currently backup to a different NAS AND an external HDD RAID5 enclosure, but in the future I may want to back it up to the DNS-321 instead and it would be very bad if I was backing it up and then needed to restore it and found out that it was unusable because EXT3 could not properly read it.
I am going to assume that EXT3 will have no issues storing a copy of a PST, but that Outlook will run into trouble trying to read/write to a PST file that is stored on an EXT3 formatted drive. But to be safe I am going to create a test .PST file, copy some emails into it, then copy it to my DNS-321 and see if I can then copy it back to my windows box and map it in Outlook, I will post back with the results. Makes you wonder what other types of application specific files does this apply to? Quicken database files would come to mind right away. Just further proof that you should ALWAYS TEST your backups out and make sure they will work BEFORE you actually need to use them/rely on them. Yes that sucks in a way but IMO there is no such thing as a device that you can simply copy files to or hit a button to backup files too and then not think about again until your drive fails and you desperately need the data back. But I someone who has seen too many people loose important files too many times to risk it myself. Perfect example is a friend of mine who had his laptop drive fail and lost many media files but more importantly work related documents/emails, he then under my advise purchased an external HDD but against my advise began to backup his system just using the "one touch easy button" many drives have these days. Well his laptop drive failed again and guess what happen when he went to restore his data, there was an old outdated copy of his stuff from what appeared to be the first backup the drive ever did but nothing after that, and even worse the files were saved in big chucks of archived ISO/ZIP type files as the drive was formatted FAT32 none of these could be over 4 GB in size so there were a ton of them with files scattered across each one.
Call me paranoid but I am a guy who runs a 500 GB RAID1 Array on their primary system and keeps the most important stuff there including documents, music and pictures, then has two separate 1 TB drives for media, one for movies and one for TV shows (don't keep all your eggs on one basket theory). I then keep a backup of all the data from each of those drives stored on a 4 TB Lacie Big Disk NAS which is configured JBOD and then backs up all the data from that NAS onto a locally attached "DAS" device that has three 2 TB drives in RAID5 for 4 TB of storage total. In case anyone is wondering that device is the Promise Smartstor DS4600
http://www.guru3d.com/article/promise-smartstor-ds4600-das-review-test/1
And also if anyone is wondering what I use my DNS-321 for it is my media box, in other words another copy of all my music/movies and then whatever TV series I am watching at the time live on there. This serves as yet another backup but mainly it serves up the media to my Western Digital Live and PS3, one of which is hooked up to my Projector and the other my bedroom TV.