Consider reading this closely related article first:
This weekend, I took a perfectly innocent Mediasonic HFR2-SU3S2 PRORAID 4 Bay Enclosure with USB 3.0 & eSATA, attached to a VM with USB 3.0, and pop out one of the RAID5's 4 drives. That seems kind of mean.
But, the experience did reveal the true nature of this enclosure, and how it handles a single drive failure.
First, get started with a peek at all the specs and pictures, including stated 3TB drive support:
and active forum here:
Now, proceed to watch the video below, if you dare. You'll get a good look at exactly how this enclosure this handles the incident, and where it fell a little short, including:
- trying to figure out why drive spontaneously disappeared from Windows when in the drive-missing state
- workaround for that bump in the road, no data lost, but a little time and confidence was lost
- doing disk benchmark testing while the array is missing a drive (enclosure can handle hot removal, I went the cold route)
- doing disk benchmark testing while the array is rebuilding after 4th drive is re-inserted
More lessons learned?
- It seems to work.
- Easy initial configuration.
- The RAID5/USB 3.0 speed of about 175MB/sec reads and 125MB/sec writes is respectable.
- Indicators do indicate rebuild and other status
- Data survived my basic testing
- Seems to handle my 1.5TB Western Digital Green drives just fine, but I did turn off idle timeouts before installing, described here, by attaching the drives to SATA ports on an old system, booting to DOS, and running this command:
- I own a second identical enclosure, and tested Mediasonic’s How to move set of Raid drives from old unit to New unit and it worked (not recorded on video though)
- No software notification of an issue.
- Support is limited to Mediasonic forum or email.
- Not sure I know how to tell which drive is failed.
- I seemed to have experienced a spontaneous disconnect, but only when a drive was ejected. This reminded me of a long time ago, when USB 3.0 was even more immature, see that saga here
- I didn’t figure out why it did that, but I did figure out a quick workaround.
Well, the shortcomings are disclosed by numerous reviewers on Amazon. You aren't automatically notified when there's a situation. It doesn't tell Windows, it doesn't tell Windows Event Viewer, it just doesn't tell you. So you have to be looking at the colorful LEDs on the unit itself to figure out what went wrong, not ideal for an out of the way server.
Also, I'm not yet at all clear how to determine which drive of the 4 drives has failed, since my test did not turn on the LED next to the drive bay, until after I re-inserted and rebuild began, seen pictured below:
Finally, there's no expansion or shrinking capabilities, you either try to keep your RAID5 array going by replacing a failed drive with a same-or-bigger drive, or you reset the RAID array and start all over, loosing all data on the array. Also note that RAID6 may be far better as far as overall failure rates than RAID5, described very well at:
but RAID6 isn't available on this enclosure.
For my needs, none of the drawbacks were a deal breaker, and to learn more yourself before considering buy, I'd suggest a thorough look at the basic Mediasonic HFR2-SU3S2 instruction manual can be found here, or their site's full pdf manual, or a 20-30x faster copy of the same full pdf manual.
For under $200, you do get a sturdy, aluminum enclosure, and you don't have to worry about port multiplier capable eSATA compatibility (the array is seen only as one drive, there is no JBOD mode that allows each drive to be seen separately). Or just use USB 3.0.
This enclosure is probably best for a secondary copy of your data, which is exactly my intended purpose, a place to store 4TB of daily Windows Home Server PC backup files, that'll be synced offsite, described here: