hi guys. good read.
im not too sure an online backup is preferable here, given the rate of growth you will experience, and the costs involved.
personally i would focus on 2 things.
1. using the mac pro continually as the "primary backup" device for your home network. this would be done by first upgrading the internal drives, potentially to 2TB or 3TB disks (slower, green drives would be appropriate, given that speed does not matter). this would either be via RAID0 or JBOD.
2. ensuring that this backup device itself is redundant. this would involve either a 4-bay external fw800+eSata+ethernet enclosure (RAID5) OR 2x dual external enclosures configured in RAID0 or JBOD (6TB max currently) (maybe take 1 offsite to a family members house to ensure off-site backups, monthly?).
this would leave room for expansion. if a quad bay is used, it could be expanded to 9TB of redundant RAID5 data. plenty for now?
oh, and a few points to note.
- RAID0 allows for fast write and read rates, RAID1 is the one that does not (just a technicality mentioned in the 3rd post i think)
- i am fairly certain that osx cannot do software RAID5 out of the box.
eh. just some ideas. and very cost effective solutions too. this could be done for <$500.
If you're referring to my setup, here's the executive summary:
Mac Pro running Lion Server is the Time Machine backup device for all the Macs in the house. It had been running 5x1.5TB WD Green drives in an internal RAID 0 as the storage volume with separate share points for each network user configured via Lion Server. Had to choose RAID 0 as OS X doesn't support software RAID 5. Four of the five RAID drives are in bays 1-4 and the 5th (as well as the Lion Server OS/boot drive) are attached to the extra two SATA posts on the '06 Mac Pro's motherboard.
Given the volatility of RAID 0, I had been looking for a way to easily add the RAID 0 array to a RAID 1 with separate external device as the other drive in the mirror. However, this proved not possible without moving the RAID 0 to an external device and buying a second matching set.
So, to minimize costs, I purchased an OWC Qx2 RAID enclosure, which supports hardware-based RAID 5, and four 2TB WD Green drives. This itself was about $760. The 8TB set gives a formatted capacity of 6TB in RAID 5 configuration. It's connected to the Mac Pro via a PCIe card eSATA connection.
Logging in to the file server as root, I disconnected it from the network for a day and duplicated all the data from the internal RAID 0 to the external RAID 5. Root was the easiest way to ensure all permissions were carried over properly. Once done, I changed Lion Server's share settings to point to the RAID 5 instead of the internal RAID 0 and connected it back to the network. The client computers were unaffected by the changes and continued along on their merry way.
I then set up the app SuperDuper! to do a Fast Copy (i.e., only files that change) from the external RAID to the internal RAID. This runs automatically 4 times per week, though I probably could do it daily since it's a pretty fast process (avg. 20 min, 45 min tops, so far).
Interestingly, even though the file server sits running on a standard Administrator login, SuperDuper! needs
root privileges (not just admin privileges) to successfully complete a copy cycle or it'll fail. Not sure why but I'm not too worried about root being active - the machine is physically secure and has (a) it's firewall activated and stealthed, and shut down to anything that isn't necessary for file sharing and Time Machine; no mail, directory, iCal or other services are running, (b) is behind a NAT device with no port forwarding directed to the server itself, and (c) is not configured for remote management.
So, bottom line is a RAID and a backup RAID, where the primary is a RAID 5 array (protected from single-drive failure) and the other slice is a RAID 0 array. While not a true RAID 1 in that there isn't simultaneous writes across both sets, the worst that could happen - in the event of
two simultaneous drive failures in the RAID 5 array - is that I'd still be left with an intact data set that is at most 48 hrs old. I can live with that. A single drive failure in the RAID 0 would destroy that array, but really just holds a backup of the other RAID set, so that could be rebuilt with zero down time.
The only thing that isn't covered is catastrophic loss/damage to the whole file server system (the Mac Pro and the 10 hard drives attached, 9 if you don't count the boot/OS drive). For this I'll need to spend some more $$ to rotate out a copy weekly on removable (or detachable) media. Not sure if a single 4TB HD will hold a full copy - if it will, it won't for long - so I'm suspecting I'll need a 6TB two-drive RAID 0 (easy to come by) to duplicate everything on to which I then can store at the office for safe keeping.
This hopefully will be helpful to someone.
Future upgrade may include a second, matching OWC Qx2 box which will get set as a software RAID 1 with the existing Qx2 -- a RAID 1 where each of the two slices is itself a hardware RAID 5 -- and ditch the RAID 0. That would be slick.
