I've just migrated my storage from loose drives to a Pegasus Promise r6 (Thunderbolt1) with 4x 6TB (2 bays not currently in use) in a RAID5 configuration with 18TB accessible capacity. Compatibility of drives has been confirmed.
I am however experiencing very low read/write speeds in the range of 60-100Mb/Sec when it should be over 400+. RAID synchronisation is finished and only spotlight (os x) is doing its indexing at the moment. Stripe size is 1Mb and express config (choosing video server) was chosen on initial setup of the RAID.
I have currently 2TB free space.
I'm fearing that I will need to set it up differently...
What is your RAID5 configuration for your Pegasus Promise (1 or 2) r4 or r6? What speed do you get?
A follow-up, I eventually scrapped custom config, added another 2 drives to a full 6x6TB, used default settings and it now runs smooth and really fast. It seems that trying things out of the box, quite literally, doesn't always result in improved performance/stability.
It now reports about 450-500 mb/sec write and 650-750mb/sec read speeds (at 40-60% full storage capacity) over T1 in the r6/Thunderbolt1.