Transitioning to RAID 5 -- Please Doublecheck My Approach

Discussion in 'Mac Accessories' started by Bryan Bowler, Nov 3, 2014.

  1. Bryan Bowler macrumors 68040

    Sep 27, 2008
    After a lot of research on my end, I thought I would run my thoughts by my fellow forum members to see if I've done my homework correctly.

    My situation:
    I used to be a serious photography enthusiast that has now transitioned to being a full-time photographer. I also shoot/edit 1080 videos in another area (unrelated to my photography pursuits) and the video work accounts for about 10-15% of my income.

    Current equipment:
    Later today, I'm picking up my new 5K iMac: i7, 32 GB RAM (Crucial), M295X, 512 GB SSD. I also own a rMBP: i7, 16 GB RAM, 512 GB SSD. I currently use a 3 TB TimeCapsule for onsite backup, and I have a large standalone hard drive that I use for off-site backups that I routinely perform every month. When traveling, I also utilize a LaCie Rugged 1 TB hard drive (USB 3) for mobile backups and transfers.

    Questions about the direction I'm headed:

    1) After a lot of research, I've decided to go with a OWC Thunderbay 4 RAID 5 array. I've narrowed down my choice of storage to either 16 TB or 20 TB. Accounting for how RAID 5 works and also the formatting of the drives themselves, the 16 TB option would give me approximately 11 TB of storage and the 20 TB option would give me 13.8 TB of storage. However, once you factor in the unwritten rule of never exceeding 75% of a hard drive's space if you want to maintain fast I/O speeds, then effectively, I would need to stay within 8.25 TB (for the 16 TB option) or 10.35 TB (for the 20 TB option) to maintain ultra-fast read/write speeds. Have I analyzed this correctly?

    2) Have any of you seen the Thunderbay series go on sale over the Black Friday period? I hate waiting another 5 weeks for my RAID array, but I'm willing to do so if I can get it for an even better price. (It has been an expensive month!)

    3) As a side note, I am aware that a RAID 5 array provides fault tolerance, but is not suitable as an actual backup strategy. My backup strategy is to continue using my large standalone hard drive to backup my data and store off-site, but I'm also considering the possibility of transitioning to an online cloud backup solution such as Crashplan and then ditching the off-site standalone drives. No real questions per-se on my back-up strategy, but of course I welcome any opinions anyone may have.

    Thanks for the help on any of my three questions above. Virtual beers and pizza coming your way!
  2. ColdCase macrumors 68030

    Feb 10, 2008
    Most in the know will advise against RAID5 for large drives, especially in a hardware RAID. It just takes too long to recover and the proprietary disk format nature is way constraining in the long term. I would simply use RAID0 with a backup or perhaps RAID 10. Get yourself two 6TB drives and RAID 0 them for 12TB. If you must, RAID0 another pair of 6TB drives and mirror them (all can be done with disk utility).

    The thunderbays rarely go on sale, but the previous version (TB1) may still be in their clearance page. Save some cash and don't buy the enclosure with built in RAID hardware.

    On line backup outfits like crashplan will choke on large file sizes. They are not set up to efficiently work with massive amounts of data and its not their business model.
  3. Bryan Bowler thread starter macrumors 68040

    Sep 27, 2008
    Thank you very much for the feedback. It's very appreciated!

    I considered using two drives in the Thunderbay in a RAID 0 configuration and then mirroring those to Drives 3 and 4 in a RAID 1 for redundancy, but I assumed my I/O speeds would not be as fast with a 2-drive RAID 0 versus a 4-drive RAID 5. The RAID 5 would be 30% faster (+/-), right?

    When you say that RAID 5 arrays take too long to recover, I'm assuming you're referring to rebuilding the array after a drive failure, right? I'm assuming SoftRAID can rebuild a large array (say 6 TB or so) within 24 hours...or am I off the mark?

    Thank you for the advice on Thunderbay pricing and online backups.

  4. glenthompson macrumors 68000


    Apr 27, 2011
    Another issue with using Crashplan is the recovery time in the event of a failure. It mays take days to get your data even if you have them send you a drive with it.

    I'm in the middle of backing up my media drive to Crashplan. It's taking months since I have a 300 GB data cap on my Cox account so I limit the backup to about 7 GB per day. It should be done by Xmas. Since I have an unlimited family plan I figured I might as well use it.
  5. ColdCase macrumors 68030

    Feb 10, 2008
    A pair of fast 7200 RPM drives in RAID0 with Thunderbolt is more than sufficient for real time editing of 1080P video, they may be loafing for Photo editing. Three drives in RAID0 would be faster than four in RAID5 as there is no parity to calculate.

    Recovery time depends on the CPU horsepower (or the hardware if you buy a hardware RAID), and both drive access and the machine will bog down to a crawl during recovery.. making them pretty much useless.

    I have two enclosures daisy chained, one populated with drives RAID0'd for real time editing, the other as an identical mirror. If need be I can switch over quickly and keep working, although I've not had a failure in years. I fill left over slots with enough drives (slower) for backup.... but thats just me. Previously I have had way too many bad experiences with RAID5, not so much losing data, but losing time. That issue has become more of problem with now larger drives.

    If you don't mind spending some time off line recovering from your backup, then you can skip the mirror part.

    But there is a dozen ways to skin the cat, it just that larger relatively inexpensive drives have changed the landscape a bit.

    You may want to keep in mind that TB enclosures are reliable, but you may not want to be off line if it needs repaired or to replace a blown power supply. It may be prudent to use two enclosures anyway. Again, if you can stand the down time, not a significant issue.

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