mounting DroboPro volumes from QNAP

[cryptochrome]

Hi there,

I have two Drobo Pro boxes sitting here, and recently purchased a QNAP NAS (TS-870 Pro) to act as a "frontend" to the Drobos. The idea is to attach the Drobos to the QNAP and share the Drobo storage through the QNAP, to benefit from QNAPs features. The QNAP is linux based and has an iSCSI initiator (which they call "Virtual Disk"). 

So here is the problem:

I can mount any "smallish" Drobo volume on the QNAP without problem. However, as soon as I try to mount a 16 TB Drobo volume, I am getting an error that says the maximum volume size must be 16 TB. The QNAP does not support mounting volumes larger than 16TB. However, the Drobo volume is exactly 16TB (regarding to Drobo Dashboard). 

So it looks as if either the QNAP is misinterpreting the volume size, or the Drobo is in fact reporting a larger volume size than 16TB.

Any ideas?

Thanks :)

[Parfumeur]

Congratulations on selecting QNAP, a recoverable RAID system, while Drobo, when failed is guaranteed to loose EVERYTHING.

I have a QNAP, after Drobo failures, and since I still have the black boxes, I keep them to back up the QNAP, just in case!  Remember that you can tell the Drobo to be larger than the actual drives in the system, for future expansion.  I have no idea how Drobo reports back to the QNAP, but do bear that in mind, that what is in the box is not necessarily how you originally formatted the Black Box.  Do you actually have 16tb in the Drobo??? Maybe you told Drobo a higher number 16tb, thinking of future upgrades, but have less than 16tb?  The Dashboard reporting and file mapping is "lalaland" in Drobo's which is why it is guaranteed to fail and be non recoverable.

Sorry for the idle talk, just wanted to remind you that about Drobo.

--
You received this message because you are subscribed to the Google Groups "drobo-talk" group.
To unsubscribe from this group and stop receiving emails from it, send an email to drobo-talk+...@googlegroups.com.
To post to this group, send email to drobo...@googlegroups.com.
Visit this group at http://groups.google.com/group/drobo-talk.
For more options, visit https://groups.google.com/d/optout.

--

-= Cß =-

[Peter Silva]

I have a little qnap also with a sans digital tr8m for additional external storage works very well so far.

For your 16 tb problem... You need to know that Drobo only supports up to 8TiB With ext3... You have to use HFS+ for a 16 TiB fs.  I suspect if you use stock firmware on the qnap, then it is always ext3. That's one reason why it might not work.

Another reason is base 10 vs. Base 2 arithmetic... Drobo uses strict base 2... Many others use base 10. So drobo's Tb might be bigger than qnap's

No suggestions come to mind kind of WAD. Works as designed

[cryptochrome]

Thanks guys.

The volumes are actually formatted using HFS+, and the volumes that won't mount are those that are 16 TB. I have a couple of smaller volumes that are only 2 TB, and they mount without problem (also HFS+). And the QNAP recognizes them as HFS+ and they work flawlessly. The QNAP "Virtual Disk" feature apperently supports more than just EXT3.

It's just those 16TB volumes (of which I have two) that won't mount because the QNAP says they are too large. 

I do have more than 16TB of storage in the QNAPs, but the maximum volume size is 16 TB. I am using the rest of the storage through those smaller volumes.

That base 10 vs. base 2 makes sense. Might very well be the case. I am going to open a ticket with Drobo. Let's see what they have to say about it.

If they can't come up with something, I am probably going to create a few more smaller volumes, see if I can mount them and them move the data to those new volumes. What a pain.... 

[Peter Silva]

  The ticket to open would be with qnap to know what their tb are.

Drobo is base 2 for sure

--

[Sascha Picchiantano]

Ok, so I opened a ticket with Drobo and asked how they calculate and present volume size. First they gave me the usual BS in the likes of "The DroboPro does not support Linux, you shouldn't do this". With some persistance, I got this out of them:

"the volume size is calculated in base 10 internally in such a way that we reach 16TB in base 2. To make a long story short, the Drobo Volume created via DroboDashboard will be reported as 16TB in size but actually have around 16TB+ (sometimes more depending on the age of the Host) in real size."

I went back to the QNAP and found some inconsistencies on that side as well: 

I mounted one of the smaller Drobo volumes and then rebooted the QNAP. When it came back, it automatically tried to re-mount the Drobo volume, but it picked the wrong LUN and instead of mounting the volume I specified before the reboot, it had actually mounted one of the 16TB volumes. WTH? I disconnected and then tried to manually re-mount the very same 16TB and get the same error message as before. So I can't add the volume manually, but when the QNAP picks it automatically (and wrongly) it works. It also suddenly reported 5 LUNs on the Drobo while it actually only has 4. 

The next wierdness on the QNAP side is that as soon as I try to mount more than one Drobo volume at the same time, it gives me another error saying that there are no more LUNs available on the target.

This isconsistent, seemingly buggy behavior on the QNAP led me to the conclusion that my data is worth too much to get lost in this process. I decided to shell out some more money and ordered a couple of WD Red 6 TB disks. I am just going to copy all the data from the Drobo over to the QNAP to be on the safe side. A real pain in the back, because that's not what I wanted to do. Oh well.

[Parfumeur]

Wise move.  Get rid of the Drobo, or GIVE them away to your competitors <g>.

--
You received this message because you are subscribed to the Google Groups "drobo-talk" group.
To unsubscribe from this group and stop receiving emails from it, send an email to drobo-talk+...@googlegroups.com.
To post to this group, send email to drobo...@googlegroups.com.
Visit this group at http://groups.google.com/group/drobo-talk.
For more options, visit https://groups.google.com/d/optout.

--

-= Cß =-

[cryptochrome]

I will happily burn the two Drobo Pros that I have on the next campfire and make shamanic dances around it while they smoke.

[cryptochrome]