Summary: APC UPS units are very reliable, work 100% of the time for us. I prefer to buy the units with the outlets on the back. The UPS's that have the plugs on top have had debris including spent staples fall into the outlets.
Summary: See the following user reported guide about the APC Back-UPS CS 350 BK350EI, as this one (BK500BLK) appears to have the same issue: http://forum.synology.com/wiki/index.php/User_Reported_Compatible_Uninterruptible_Power_Supplies http://www.apc.com/site/support/index.cfm/faq/index.cfm "AS correcty shuts down to safe mode when UPS goes on battery, with settable delay. NAS correctly puts UPS in sleep mode after going to safe mode.
Pros: Seems to work plug and play with my Synology DS1513+. With just the NAS plugged in to the battery, at 100% battery I get an estimated ~2812 Seconds reported to Synology.
Cons: After simulating power failure by unplugging the UPS, I checked my reported battery level and within 1 minute I had dropped down to ~75% of battery. I tested it again and left it running longer, under 5 minutes (with the NAS in safe mode) and it only seemed to drop to ~65%. I thought that I had bought more than enough battery for my NAS power usage, so I'm left wondering if the UPS power levels are not reported correctly.
Summary: I've had my unit for a few years now. The battery has finally gone out. Easy replacement. I got a warning alarm from the unit that was telling that the battery needed to be replaced which is handy. Plugged in the new battery and it works fine. Unplugged the unit and my computer didn't even blink.
Summary: I have always used APC and NEVER had any problems. It's the only reason I pay their higher prices.
Pros: Easy install, no noises coming from the unit. Windows Vista detects it as a battery without the need to install the included software (please don't ask about the Vista). Can now image customer drives and make backups without worrying about power loss. If you do decide to install the included software, it works well enough. Though it's not needed it does provide statistics on power usage and available battery time. If interested it also tells you how much the power is ...
Cons: Very little room for transformers. I have a laptop, external HDD, and a HDD dock attached to the battery side. The dock and external drive have large transformers so a powerstrip was needed. (I don't like to plug one surge protector into another) I only get between 30 and 35 minutes of battery, so if a data transfer is running over night and the power goes out for more than 30 minutes I'm in trouble. But that's more of my budget talking than an actual con of the device.
Summary: We have 14 of these backups, one on each workstation at our business. We've tried other backups over the years, but these are the ones that last the longest. And it's relatively easy to replace the batteries.
Summary: This is a nice compact unit. I like having the outlets on the back of the unit. One of my UPS units has the outlets on the top and they get dusty. I will replace it with one of these when the battery fails.