Apple APFS and Removing Drives From Your JBOD RAID

JBOD drive case copies data on Apple APFS JBOD RAID

I did a bit of searching for if its possible to remove a failing drive from an Apple JBOD RAID. Its all theoretically possible. I’ll also admit having some ZFS envy. MacZFS turned out to be a bit of a bust in terms of usability. I couldn’t format a dataset volume that without error in Disk Utility and I wasn’t going to get into deep terminal work to make it work. Going back to Disk Utility and just messing around with a few drives formatting them in various way, I finally figured out how to remove a failing volume in a JBOD RAID.

First a few clarifications. You have to format the JBOD using OS X. If you did it via drive case firmware, this isn’t going to work because there is no access to the underlying utility or drive controller.

Another is that you need to have enough free space in the JBOD to hold whatever is on the drive you want to remove. If you want to remove a 6TB drive then you need at least 6TB of free space to do this successfully. Having a 5 to 10% margin of additional space would be a good idea for just in case things don’t fit down to the last few bytes.  Workaround if you don’t is to add another drive to the JBOD to give it space to internally shuffle the data around in the next steps.

Cost of failure : you loose all your data on the JBOD if the operation fails. This is a rough one but I think Apple’s diskutil is still a work in progress in this area. It apparently does check the space situation but if you try this and it throw up a warning there isn’t enough space, I’d take that warning seriously.

Odd limitations :

  1. Disk Utility requires that there be at least 3 drives in the JBOD for this to work. If you have just 2 it won’t let you remove a volume. So you may need to add a drive just to remove the other one.
  2. Disk Utility only allows you to remove the last mounted drive in the JBOD set. I. know this seems weird since you really should be able to remove any volume except maybe the first one which holds the directory and other RAID metadata. There is a workaround.

Workaround: Figure out which way your drive case or dock is physically mounting the drives, top to bottom or bottom to top, left to right or right to left. How ? unmount the RAID, power down the case and remove a drive at the very top or bottom, right or left. Power the case up and see which drive is now reported missing in Disk Utility. If its the top most disk in the list, the drive on the other end is the last. Knowing this, unmount the drive although its probably not mounted right now, power it down. If you know the physical volume you want to remove due to say, SMART error or simply making noise, move it to what will be the last physical drive slot to mount. Fire everything up and it should mount.

Now one thing I have seen is that with JBODs if you don’t have the drives in the order they RAID was built, it might not mount. Put the drives back in with appropriate power and unmounting. Once it mounts again, power down and move the drive back. On second tries I’ve had this work with seeming random order of drives. In particular maybe the actual issue is getting the first drive of the set into the first slot to mount and then it doesn’t matter.

Once you have the drive you want to remove in the last physical slot to mount and have the RAID mounted.

  1. go to Disk Utility, Select the RAID set
  2. In the view of the volumes that are in the set, select the last one in the list which is presumably the drive you want to remove. If not, unmount, power down, swap drives and repeat until it is.
  3. If the selection is good, hit the Minus button on the bottom left of the window

  4. A warning will come up about the operation may fail and you’ll loose everything if there isn’t enough free space, Click Remove
  5. Wait.

  6. Disk Utility will now copy any data from the drive to be removed back onto free space across the other drives. This may take quite a few hours depending on your case interface and drive speed plus how much data needs to actually be moved around. If you can use an eSATA or USB 3.1+ interface it’ll be a lot faster than USB2 which could take days. Unfortunately Disk Utility doesn’t provide any sort of progress bar, estimate to completion or any other indication how long it will take. You simply repeat step 5 until its done. Fair warning – don’t write anything to the RAID while this operation is going on. Given that things like large block sizes can inflate how much space small files eat up don’t start this operation unless you have a little margin on free space.

If all went well, you should till have your data and the drive you wanted to remove can now be physically removed from the case and everything works.

What if it didn’t go well ? That happened to me the first time where the operation ended after 8hrs of moving bits around. Disk Utility simply displayed “An error has occurred -69000 something”. DU also was beachballed requiring a force quit. I rebooted since DU was in a hopeless state.

Once I got back up, I opened up the array I was trying to trim the drive from. I decided, as a guess there wasn’t enough free space and that DU had already shuffled most of the data off the drive I wanted to remove. I found a project using 1.15tb of space and deleted it. I had 2 other copies of it and this was the headline restore version. It could go as could a few hundred gigs of other dead projects. I now how another 2tb of free space and decided to try again. Note : NO data loss despite DU’s dire warning there would be. My good fortune may not be yours, proceed with caution.

With more space free, I opened DU yet one more time. I set up the remove operation and went to bed. I have no idea how long it ran for, at least 20 mins. In the morning it was done, no error message. In fact DU said it was safe to remove the physical volume now. The JBOD I had removed the drive from showed the correct volume size. I had to reboot again because, well, I actually did remove the drive from the case and that caused DU to again beachball. Once restored, everything was good. I could now reuse the drive from the original array an move it into the new one. Yes folks, this does work with some tedious time and effort. You might need to decide if the time and risk is worth it versus just buying a new drive or several and copying everything over. That is of course assuming things are in working order. If this is a salvage operation, there isn’t any backup and you are trying to save the data this process might be worth while – add a new drive, mess around until the failing drive mounts last, then use DU to remove it from the set.

DIY Quick Fixes For Your Busted Letus Hawk

For $400, ( Ok, B&H has them on special for $349 ) none of what I’m going to reveal next should be needed. The repairs I’ve done and problems I’ve had are to be expected from something at maybe 1/3 of the price where you can say ” well it was cheap, and the fix wasn’t bad, some I’m ok with it.”

When I first got the Letus Hawk LCD Viewfinder Loupe, the mounting holes stripped out. The inserts in the very sexy carbon fibre body are soft steel. My next replacement had ok inserts, but some weird blob, probably fungus developed on the inside of the lens. Ok, third time is a charm, right ? Well yes, for a while.

After a bit of use, the hex screws came loose. I tightened them, and one of them stripped out again. This time, I just wasn’t in the mood to exchange the unit again, even if it is covered under warranty. Instead I realized that since the bracket design was flawed, I needed to come up with a better idea. The fix was very simple, epoxy. Given that the body is carbon fibre, its made of either polyester or epoxy resin. Epoxy will stick to either very well, and I had some good quality epoxy that dried glossy black.

letus hawk DSLR viewfinder magnifier fix
letus hawk DSLR viewfinder magnifier fix with black epoxy

First I cleaned up the hood body by wiping it off with paint thinner, and letting that completely evaporate. Next I actually glued the rubber gasket on using ACC ( crazy glue ) by running the glue around the inside of the rubber bumper. I slipped the bumper onto the loupe body and this just isn’t going anywhere.

Next in the area where the metal bracket meets the loupe body, I sanded that area a bit to improve the bonding area.

I slid the loupe bracket into its socket on the camera, and made sure it was sitting the way its supposed to, and then placed the loupe itself on the LCD screen in proper alignment.

Finally I mixed up the epoxy, about a teaspoon’s worth, and applied on the area where the bracket mounts to the loupe body. The epoxy I had was very thick, and I applied a pretty small amount to just cover the immediate bonding area. Since I was working above the actual camera LCD screen I was being super careful about not dripping or squeezing out any epoxy onto the screen surface.

letus hawk dslr zacuto viewfinder
I then screwed in the two screws, each with some epoxy on their shafts. Even though one was stripped out, it still gave me some grab, and the steel pin glued in place doesn’t hurt anything.

With the remaining epoxy, I globbed it on and around the metal bracket and out onto the loupe body for additional bonding area. I also got epoxy into the screw slots in the bracket to again help with getting  the best bond I could. Epoxy does have body strength and I was just taking advantage of it.

I let it dry over night, and so far, so good. It looks like I’ll now have a solid dependable connection that isn’t letting go all the time. Sure its hard to design small reliable brackets likes this, but this is old ground in engineering. The answer is simple : hardened steel or stainless steel, not the cheap soft steel screws and inserts that are currently used. Also, if you haven’t yet stripped out your screws ( it takes 2-3 adjustments to do so in my experience ) you can add a #4 washer ( read really small ) between the screw and the bracket. This will stop the bracket from moving away from the camera when you tighten it the one or two times that you can.

So my word to Letus is : get some hardened stainless steel bolts and inserts, or just change the mount completely… please ! the great optics deserve a better mounting system.

How To DIY Fix Your Intuos 2 Wacom Pen Button in 30 Seconds

I’ve got an Intuos 2 tablet that I “restored” a few years ago by getting a new pen surface for it, and some replacement pen nibs. While all of that works fine, the button on the pen simply falls out every ten minutes making using it far less then ideal, but hey it works. I finally got curious and frustrated enough to find a really really simple fix that has made the pen perfectly usable again, and the button hasn’t fallen out since !

Getting Your AMD / ATI GPU To Work In Premiere Pro CS6

On thing that may of been missed by a lot of folks in the release of Premiere Pro CS6 – support for real time full res full frame effects by using OpenCL in Mercury Playback Engine. Almost everything thats done with CUDA on nVidia cards is also now being done as well in OpenCL on ATI / AMD GPU’s. Read more on adobe site for the details
A Little Hacking To Get Your GPU To Work
The list of supported GPU’s is short – just 2. However its pretty easy to get your own GPU to work provided it meets the major requirement ( at least for CUDA ) of at least 768mb of VRAM. The GPU in my 2010 iMac is a 5750 with 1G of VRAM. A slightly older GPU, but enough VRAM to give it a go. Here is how I did it.
1. Location the actual Premiere Pro application
2. right click on the Prem Pro icon and in the contextual menu select “Open Package Contents”
3. Open up the Contents folder
4. Right click on the file named opencl_supported_cards.txt and do Get Info on the file
5. At the bottom of the Get Info window click the lock icon, enter your admin password when asked
6. If Sharing and Permissions isn’t spun down, do so
7. Change to Read & Write
8. Close the Get Info window
9. Now open the opencl_supported_cards.txt file into TextEdit. You’ll see 2 cards list there.
10. Go to the OS X’s top left apple button menu and select About This Mac
11. In About This Mac hit the More Info Button.
12. On the first screen ( Overview ) you’ll see your GPU model. Drag the mouse cursor over the text so it selects, then hit Command C ( copy )
13. Back to text edit, go to the end of the last line. Hit enter, then paste the name of the GPU in.
14. Hit Save and then close the file
15. Start Up Prem Pro and enjoy hardware MPE on your ATI / AMD GPU