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Gen 2 Drobo and 6 TB Drives
05-24-2016, 08:46 PM (This post was last modified: 05-25-2016 04:20 AM by AzDragonLord.)
Post: #1
Star Gen 2 Drobo and 6 TB Drives
I just received a "new" white-label 6 TB hard-drive and plan to perform a surface scan on it before I place into production in my Drobo5N, but I had to try something first...

I know the latest firmware (1.4.2) for the Gen2 "officially" supports drives only up to 4 TB. I decided to dig out my old Gen2 Drobo, populated it with small (750 GB or smaller) drives and made sure it was working and my dashboard (version 2.8.1) was seeing it with no issues.

At this point I removed one of the hard-drives and replaced it with my new 6TB drive. Within seconds the Gen2 Drobo recognized the larger drive size and adjusted my usable capacity appropriately. Smile I don't know how it would handle an 8 TB drive, but I suspect it would be similar.

Though not "officially" supported, I hope this will show that older Drobo boxes still can have options beyond their original 4 TB drive limits.....of course the maximum volume size is still 16 TB.

Drobo (Gen2)
Drobo 5N
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** Praise the Gods, Do Good, Act Bravely. **
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05-26-2016, 04:18 PM (This post was last modified: 05-26-2016 04:19 PM by Paul.)
Post: #2
RE: Gen 2 Drobo and 6 TB Drives
thats cool and interesting news Smile

its always cool to try some tests (as long as they are safe tests with backups etc)
one of the tests im interested in trying out at some point is to try and establish which 3rd party tools can be run on a drive that has been yanked out of a (powered down drobo) disk pack, in a non-destructive way, and then put that drive back into the still powered down drobo, to verify that all is still working fine. (but to get to the safe state i need to back up all data, get the tools, and get my gen1 back to a working state, now that i recently got my drobo-s-gen2 all fine again)

ideally, it will be good to simulate or to have the drobo experience any processes that it usually might experience, in order to do a fuller set of tests now that the 1st test seemed ok, but if you have any more info on how things go, you could even capture some clips for youtube...

after all - we already have your "dragons den" - why not a "dragons workshop" Big Grin

(btw i have XP home SP2, a Drobo v1 with 2x 1TB/2x 1.5TB WD greens, & a bkp Drobo v2 with the same + a DroboShare: unused)
& a DroboS v2 with 3xWD15EADS &2x1TB in DDR mode on win7, & a drobo5D (all usb)
  • btw i did a sustained (write) operation for about 6 hours, and got 13.2MB / sec ...objection? "sustained" :)
    (16.7MB/s on a v2 & 47-96MB/s drobo-s)
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01-11-2017, 03:23 PM (This post was last modified: 01-11-2017 03:29 PM by AzDragonLord.)
Post: #3
RE: Gen 2 Drobo and 6 TB Drives
This morning I replaced a 750GB drive in my Gen2 Drobo with a 6TB drive. It's reporting the drive size and the proper available capacity with no issues......so far. Since this is nothing but backup data for the 5N, I'm not worried about it breaking.

It will take a couple more days before the rebuild is completed. ::fingers-n-toes crossed::

Drobo (Gen2)
Drobo 5N
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01-11-2017, 06:07 PM
Post: #4
RE: Gen 2 Drobo and 6 TB Drives
nice one dragon, just linking your screenshots page here:
http://www.drobospace.com/forums/showthr...http://www.drobospace.com/forums/showthread.php?

(btw i have XP home SP2, a Drobo v1 with 2x 1TB/2x 1.5TB WD greens, & a bkp Drobo v2 with the same + a DroboShare: unused)
& a DroboS v2 with 3xWD15EADS &2x1TB in DDR mode on win7, & a drobo5D (all usb)
  • btw i did a sustained (write) operation for about 6 hours, and got 13.2MB / sec ...objection? "sustained" :)
    (16.7MB/s on a v2 & 47-96MB/s drobo-s)
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08-12-2017, 03:16 AM
Post: #5
RE: Gen 2 Drobo and 6 TB Drives
I would be leery about doing this regardless of these huge drives working, at least with "consumer" drives, you run into the same problem that happens with huge RAID5 arrays when the time comes they have to rebuild.

Typical consumer drives have a URE (unrecoverable read error) rate of about 1 in 10^14, meaning on the average if the drive meets spec you'll hit an unrecoverable read once in every 12TB (ish), if that happens during a rebuild the drive it happens on also gets dropped and suddenly the entire array becomes useless and your data is GONE.

You either need to upgrade to a later Drobo that supports dual redundancy and enable it, or if you can stand the huge rebuild times consider enterprise class drives like the WD Gold "Datacentre" drives (as opposed to Red "NAS" drives) if you're going for huge sizes, as the URE rate is specified as 1 in 10^15 a whole order of magnitude less frequent than the Red NAS drives (specs read 1 in 10^14 for those), giving you reasonable odds of a rebuild completing sucessfully, though it's still higher risk than most people would want if you actually do the math to figure the chances of a URE during a rebuild.

This is why you don't see RAID5 used in data centres for big capacity arrays anymore, rebuilds fail too often! OK Drobos aren't RAID5 but it's still a single parity setup, and subject to similar failure modes.

You really are just spinnng your prayer wheels using massive consumer drives in single parity... this may have some bearing on *why* Drobo never tested or added "official" support for such setups. If you really need the capacity, there are valid reasons to upgrade and get dual drive redundancy
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