I have had a 2nd generation Drobo with Firewire 800 port before I started on the ZFS NAS project. I have been using it for a while to keep important data. It had 4 1TB drives installed and was about 25% full.
Recently, I got a few good deals on Seagate 1.5TB so I decided to replace the drives in the Drobo.
The interesting thing is this: I pop out the drives from top to bottom…. 1st drive poped and the Drobo Dashboard immediately detected the missing drive and flashed red. I put in the new 1.5TB drive and it started to rebuild. Estimate: 4 hours…
I let it run overnight and the next morning, pop the 2nd drive out and replaced it with another 1.5TB drive, I was amazed to see that the rebuild time was much lower: 2 hours.
After I returned from work, I proceeded with the 3rd drive. This time, the rebuild time was only 45min. The last drive’s rebuild time was 20min.
Looks like the way Drobo protects its data is by writing mainly to the 1st drive, distribute the content to 2nd,3rd and 4th drive so that we have at least 2 copies of every file. Obviously this is not a scientific study but an observation that leads to my believe that is the way Drobo protects data.
Probably after the 1st drive is full, the 2nd drive will be the target of new files, while Drobo continue to dupe the file to 3rd and 4th drive etc etc.
Simple yet effective… and I could be totally wrong. Regardless, Drobo is simply quite amazing (although still quite expensive).
OpenSolaris does not yet support SATA port multiplier like the Silicon Image Sil4726 or Sil3726. I tried this with my OpenSolaris NAS build. I originally had a Sil 3114 based controller card, it didn’t work with Port Multiplier. I got another Sil 3124, which supports Port Multiplier, but it doesn’t work under OpenSolaris…
Then I found this: http://www.cooldrives.com/usb20toescow.html
This works great under OpenSolaris. Speed is reasonable for a USB based solution. I have it connected to a AMS 5 bay SATA external enclosure with Sil4726 (http://www.newegg.com/Product/Product.aspx?Item=N82E16817332017&Tpk=AMS%205%20bay). This shows up great in OpenSolaris. I put a bunch of spare SATA drives into it and build another RAIDZ pool.
Not the best solution in the world, but it would work for the time being until full port multiplier is implemented in OpenSolaris.
Make sure that the eSATA -> USB2 bridge you buy supports port multiplier. Not every adapter does.
These are the guides that I followed to build one:
1. http://developers.sun.com/openstorage/articles/opensolaris_nas.html
2. http://pegolon.wordpress.com/2009/01/13/build-your-own-drobo-replacement-based-on-zfs/
The hardware:
- Old PC Box
- Atom 330 Mobo with CPU: http://www.newegg.com/Product/Product.aspx?Item=N82E16813121359
- 2GB DDR2
- PC Power and Cooling 420W Power Supply (you may want something smaller than this since the top power it draws is only about 100W. Most power supplies would not be in their high efficiency state if draw is less than 50%): http://www.newegg.com/Product/Product.aspx?Item=N82E16817703017
- 5 Bay SATA backplane: http://www.newegg.com/Product/Product.aspx?Item=N82E16817995001
- 4 port SATA PCI card: http://www.newegg.com/Product/Product.aspx?Item=N82E16816132017
- 6 Western Digital Green Power WD1000EADS: http://www.newegg.com/Product/Product.aspx?Item=N82E16822136317
- 1 old spare EIDE hard drive 250GB as boot
- 1 old spare DVD burner using EIDE -> USB converter for installation
OpenSolaris 2009.06 released! Yeh!
Have been using OpenSolaris with ZFS RAIDZ for a NAS box with Atom 330 Intel motherboard. 6 1TB Western Digital Greenpower WD1000EADS. It is surprisingly easy to setup as a NAS box and you can also purpose it for other jobs (e.g. web server). Highly recommended.
Time to update it tonight!
