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Max Capictacy still low with new Drives?
08-31-2016, 09:32 AM (This post was last modified: 08-31-2016 09:32 AM by partick@patricksmithphotos.com.)
Post: #1
Max Capictacy still low with new Drives?
Hello,
I currently have a Drobo 5D and noticed my storage was looking low despite no warning signs or indicator lights.

I replaced older 2TB drives with all 4TB drives and migration completed successfully. So I currently have every drive filled with a 4TB drive.

But then I noticed the 'Max Capacity' still reads 16TB. (Breakdown: 14.48 total....10.95 Used....3.53 TB Free).

I wanted to again add another drive 6TB to replace a 4TB, but wondering why I am not seeing a bigger Max Capacity.

Any insight would be helpful.

Thanks!
Patrick
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08-31-2016, 02:07 PM
Post: #2
RE: Max Capictacy still low with new Drives?
hi patrick,
if you currently have 5 drives of 4TB each, in your drobo, then i think the overall break down would be this:

if we assume single drive redundancy (sdr).
5 x 4TB = 20TB raw
-4TB (for sdr) = 16TB
16TB (*0.9 for filesystem overhead) = approx 14.4TB available for data.
(i think you have Sdr, and it looks like your available amount fits within the max 16TB volume size, as designed.)


If you were to swap out a 4TB for a 6TB, then your system might look like this:
6TB + 4TB + 4TB + 4TB + 4TB = 22TB raw
-6TB (sdr, which is usually the same amount of space as the largest drive) = 16TB
16TB (*0.9 for filesystem overhead) = approx 14.4TB available for data.
= no real benefit, for now, but once that rebuild is complete, if you then replace another 4TB for a 2nd 6TB, that should increase your capacity for you, (and would likely create an additional volume for you to use)
that new volume would also show you max 16TB, but please use dashboard overall for free space, because dashboard takes both virtual volumes into concideration regarding how much actual space you have.

i hope this helps, though if you would like some more examples i recently posted here for another user, as we were trying to ascertain where the values were coming from Smile
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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