I have a drobofs and have some ?'s about the performance. When trying to delete files files created from my new 27 inch imac it takes forever waiting at the preparing to delete immediately, them it will ususally error out and say i dont have permissions or the a file is locked. These files were put on the drobo with drobocopy and they are backups of my user folder. this maybe a osx problem with permissions and i am a rookie with osx. I donot have these problems with my winblows machine. Also i have yet to have a drobocopy actually complete from the imac it will usually fail or i will rebbot the computer. I had it run for 4 days straight, with power settings to never turn off. I think the actual amount of data is about 900gb. and if it matters my lan is setup like this. uverse rg-- all data to apple timecapsule-- netgear gs108 gige switch (for added ports off time machine)-- netgear gs108 (in office)
I’m under Windows XP and it takes FOREVER to delete files. I’m talking 1/2 hour to delete 200 gigs. And sometimes is disconnects and I have to restart the delete a few times. I’m told long deletes are normal for the XFS file system. 
i tested speeds and it i am getting 40mb read and 27write. the speeds were the same on local lan or direct connect computer to drobofs. it took 56 seconds to copy a 1.5 gig video file to the drobofs and 38 to copy from the drobofs
Try turn ON the Jumbo frames if your switch support it. It will slightly increase the performance.
No jumbo frames on new iMac i7
Yea … too bad then. On my Windows machine it work like a charm. 
I just set it to MTU 9000 in my Drobo Dashboard.