Post Reply 
 
Thread Rating:
  • 0 Votes - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
5D short of capacity after replacing disc
08-24-2016, 07:39 PM
Post: #1
5D short of capacity after replacing disc
I have a Drobo 5D.
It had 4 640 GB discs and a 5 TB disc in it.
It just recently reported that it was "critically short of capacity" so I replaced the indicated disc (Bay 0 - a 640 GB disc) with a 5 TB disc.
It went through its rebuild routine and now reports that it is AGAIN "critically short of space" and wants another disc replaced.

Both 5 TB discs are properly recognized; no discs are marked as bad
This makes no sense. What is wrong here?
Find all posts by this user
Quote this message in a reply
08-24-2016, 07:58 PM
Post: #2
RE: 5D short of capacity after replacing disc
hi kraavo,
can i check if your drobo is currently set with DDR (dual disk redundancy mode?)

it depend on when the 1st 5TB drive was put into the drobo, though usually the drobo will take the overall size of the largest drive, and use that amount of space for SDR (single drive redundancy) protection.

(with DDR, it would take the overal size of the 2 largest drives for protection)

in your case, if you have SDR, then you may have this:
5TB + 0.64TB + 0.64TB + 0.64TB + 5TB = approx 11.9TB (raw capacity)
-5TB of space (for sdr) = approx 6.9TB (available)
6.9TB (x 0.9 for filesystem overhead) = approx 6.2TB usable for data

when you get a moment can you post back with some more info on how much data you have as used space and how much is free space (via dashboard?)

i think if you are around the 85% used mark and 95% used marks, it would prompt you to update another drive (possibly one of the smaller 0.64TB drives) via a solid yellow light for that drive (or via a solid red light for that drive if at the higher used % mark)

(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)
Find all posts by this user
Quote this message in a reply
08-25-2016, 02:02 PM
Post: #3
Sad RE: 5D short of capacity after replacing disc
I am the OP. For some ridiculous reason I have to create a new ID every time I want to use this forum! I'm running out of email addresses to use. Sad

Anyway, to answer the question, Yes, it is set to DDR. The 4 640 GB drives went in first. The first 5TB drive went in there probably at least a year ago.

Capacity is reported as 1.72 TB with used space reported as 1.65 TB

What you described is exactly what happened. I saw a red light on the Drobo and thought it was a bad disc. The disc was reported as healthy but that I needed to replace it with a larger disc. That's when I put the second 5 TB drive in.
Find all posts by this user
Quote this message in a reply
08-26-2016, 12:24 PM (This post was last modified: 08-26-2016 12:27 PM by Paul.)
Post: #4
RE: 5D short of capacity after replacing disc
ah ok thank you for the info,
(am not sure about the forum though there were a few issues recently and it could be just that the issues affected new registrations, though if it keeps happening please do try to contact the support team as ideally once you have an account, it should let you log back in with those credentials.... maybe visiting the forum first, and then trying to login - or logging into the support portal, and then coming here, could help?)

for your drobo though, i think that it could be due to the timing and use of DDR....
for example, if we follow the previous SDR example, but for ddr, then:

in your case, as you have DDR, then you would appear to have this:
5TB + 0.64TB + 0.64TB + 0.64TB + 5TB = approx 11.9TB (raw capacity)
-5TB of space and -5TB more of space (for ddr) = approx 1.9TB (available)
1.9TB (x 0.9 for filesystem overhead) = approx 1.7TB usable for data

this appears to match what you have above

if your drobo is currently in a stable state (without any flashing lights), then one thing you could do, could be to try upgrading one of the smaller (0.64GB drives) into a larger one if you can, such as a 2TB drive, and that should give you more usable space.

(the way the drobo works, is that it is essentially protecting you against 1 drive failure, for sdr, and as you are using ddr, it is trying to protect you against 2 drive failures - but because it can not control which 2 drives could fail, it has to assume that your 2 largest drives could fail... this is why it is trying to allocate and reserve about 10TB of space)

once you are able to upgrade the smaller drives, you should start seeing a good increase in usable space.

alternatively, if your actual data is only taking up about 1.65TB, is there any way that you can copy that data somewhere else as a backup, and then once you are happy that the data is accessible via that backup...

- then you could try switching the drobo back into single SDR mode, until you can get another large drive?
(this way, you would still have SDR on the drobo (protecting you for 1 drive failure), while still having your data backed up somewhere such as a separate standalone usb drive or something, and i think you would regain about 4.5TB of usable space.

(personally, i think having DDR in place, and leaving it active, is better than SDR, and just upgrading the smaller drives, 1 at a time, over time, will give you good increases... though it is worth bearing in mind that each drive upgrade could take about 1day per 1TB of data that you have on the drobo)

(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)
Find all posts by this user
Quote this message in a reply
08-26-2016, 03:42 PM
Post: #5
RE: 5D short of capacity after replacing disc
Thanks Paul.
I guess what made absolutely no sense to me is that recently (within the last week) it decided it was "critically" short of space with 4 640 GB + 1 5 TB drives. Then decided it was still critically short of space after replacing 1 640 GB drive with a 5 TB drive. It just mind boggling that 1.6 TB of "stuff" somehow occupies almost 12 TB of space even if half is used for duplicating storage. I saw what you said about two drive failure so it does make sense (sort of). Still mind boggling.

So off to Amazon for another drive. Thx for the help and the explanation.
Find all posts by this user
Quote this message in a reply
08-29-2016, 02:19 PM
Post: #6
RE: 5D short of capacity after replacing disc
ok no problem kraavo, plese let us know how things go - and cool you got your original login to work Smile

(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)
Find all posts by this user
Quote this message in a reply
Post Reply 


Forum Jump: