Hot-swap RAID vs Drobo Questions

I have a file / print server built around OpenSUSE with 4 x 500G drives in a RAID 5. It has worked great and I share files with Linux, Mac, Windows, etc.

The RAID is getting full and I plan to pick up 4 x 1.5G or bigger drives. I have been doing some research, and have a few questions:

  1. Has anyone got a hot-swap RAID system working with SUSE? I see drive bays that claim to support it, but I am wondering if anyone has done it. It would be great if the drive lights could match status too (i.e. red if failed instead of just activity)

  2. Is getting a RAID card worth it? They are about $400+ and it seems that the software based one works fine…

  3. I like the concept of a DROBO where you can mix and match drives and add them easily as time goes on. I saw unRAID and a few other linux methods, but I am not sure it works as easily. Since changing drives hardly ever happens, I am not sure the drobo is worth the price. Although a drobo and a mini-pc running OpenSUSE might be my next file server.

What do you think? Thanks!

My personal experience is that hot-swap never worked properly on smaller systems and I had to disable the drive, shutdown, insert/replace new disk and start up.

This is not even remotely true. While it is necessary to fail (mdadm -f) and remove (mdadm -r) the drive from the array, a reboot is not required. I recently replaced the 4 drives in my raid 5 array 1 by 1 to increase capacity and never had to reboot.

I have this case, though I think it may be possible to buy the sata backplane separately (not an endorsement of the case, the power supply included is insufficient and it requires an impossible to obtain adapter plate to secure a standard atx power supply). With my motherboard, there is no indication of a failed drive, even though the drive trays have red leds.

Software raid works fine. The only way a raid card would be worth it is if it has batter backed cache for raid 5 and allows writeback caching. I’m not sure if hardware raid would allow for online capacity increases by either adding drives and restriping, or replacing all drives one at a time like software raid allows.

On that note, my hot-swap SAS array(s) works just fine in Linux although I doubt you had that in mind as it’s a bit costy.

Larger (and costlier) systems do support hot-plugging without much issues. Also, “sometimes”, you do get support. But, I specifically mentioned “smaller systems” in my post. (I should have mentioned “cheaper” too!)
Also, I had problems with some systems in the past to smoothly pull out the disk while powered on.