I purchased a Promise Pegasus R4 4TB (4x1TB) RAID System 13 days ago, along with a 27-inch iMac, Late 2012, 3.4 GHz Intel Core i7 (OS X 10.8.5). I purchased the unit to be used primarily as a backup system, via Time Machine. I decided to purchase the unit because I could get it via the Apple Store, along with the computer, and also because of the Thunderbolt interface. It was easy to connect and get it running, except that it took approximately 48 h to "automatically initialize and synchronize" (this is what is written in the documentation that came along with the unit). After selecting the unit for Time Machine, I had the first backup (really fast!). I also used the unit to store my Aperture Vault (also very fast when setting up for the first time).
I was very happy with the purchase until the morning of the third day after setting up the system. When I woke up the computer, there was an error message indicating "The disk was not ejected properly. If possible, always eject a disk before unplugging it or turning it off." First, I though it could have been an electrical problem, however, the unit was safely connected to an APC Smart-UPS 1500 and the UPS didn't shut down (the computer was also connected to the UPS). I checked all cables (power and Thunderbolt cable) and they semmed properly connected. By the way, I was using an Apple 0.5 m Thunderbolt cable.
The unit was still on, albeit unmounted. However, after several attemps to re-mount it, including disconnecting and re-connecting the Thunderbolt cable, restarting the computer, turning the computer off and on again, I tried to turn the Promise Pegasus off and, to my surprise, it wouldn't go off, no matter for how long I kept the power button pressed! Finally, I relied on brute force and disconnected the power cable on the back of the unit. After reconnecting the cable, the unit went on and mounted on the Desktop. Everything was back to normal, until the next morning... The same problem again! After waking up the computer, the same error message. I had to use the same procedure of unplugging the power cable.
After some thought, I decided to turn off the "Put hard disks to sleep when possible" option under Preferences->Energy Saver. Next morning, the same problem again!
I decided to search for the cause of the problem on the internet and found this Discussion. This made me VERY concerned about the purchase! Two days ago, I decided to move my iTunes library to the unit. After buying the new computer, I had to download the entire library from iCloud (using iTunes Match). The process took about 30 h. During this period, the computer went to Sleep mode and, after resuming, the Promise Pegasus unit was still mounted (but iTunes was still downloading music). This morning, after waking up the computer, iTunes had finished and the Promise Pegasus was unmounted again! Apparently, as long as there is I/O activity, the unit will stay mounted. After a prolonged period of inactivity (and the iMac in Sleep Mode), the RAID unit unmounts itself, misteriously.
After that, and considering this Discussion, I called Apple Support and asked for a refund. I was promptly attended and already got the return labels by e-mail. I was very frustrated with the experience, especially by figuring out that I cannot trust the quality of a product just because it is being sold on the Apple Store (never had a problem like this before!). Finally, considering the ads, this Discussion, and the bad experience, I consider this product a piece of junk, that didn't go through proper testing before being marketed.
