Netgear ReadyNAS NV+ V2 and Larger Disks (WD60EFRX)

Just want to get this out of my head so that I can go back to sleep...

I've been taking a sabbatical after 3 years with Zapp (2 years as Chief Architect) and have been doing a number of personal projects. One of the projects was to sort out my NAS setup as I was running out of space on my ReadyNAS NV+ V2 and wanted to play around with fitting larger disks.

I decided to experiment with installing non-officially supported 6TB Western Digital NAS drives as their siblings (WD10EFRX/WD20EFRX/WD40EFRX) are supported.

I can only report failure though possibly with a glimmer of hope for others...

My previous configuration had 4 x WD30EZRX (3TB) drives in an X-RAID2 setup. After backing up I started to try out hot swapping out the drives individually and resynching before rebooting to realise the increased capacity.

The first problem was that the screws that came with the ReadyNAS were A2 Countersunk UNC 6 32 1/4" screws. To mount the WD60EFRX you need 3/16" or even  5/32". A little careful work with some abrasives took care of that as I was impatient.

Over the course of 4 days of swapping and resynching (each resynch took ~16 hours) I was ready for the reboot. The resynch had gone swimmingly!

At reboot is when things started to go wrong as the expansion failed and it started resynching the drive. All reboots after resynch completion failed to expand the volume and resulted in a resynch.

Next attempt was to clear the drives down completely (including the existing partitions) and perform a factory reset (boot menu button accessed via a pinhole by the USB, choose 'Factory Defaults'). First I tried X-RAID2 default - file system creation error. Next I tried Flex RAID with a RAID 5 configuration - file system creation error.

I then decided to use the EnableRootSSH plugin and dig into the operating system to see what was going on... going into the detailed logging I saw that the creation of the ext2 filesystem on the large volume was failing.

Sleeping on it (until just now) I woke up with a realisation that ext2 is quite an old filesystem and may have some limitations. At a 4 KiB blocksize (which is what is configured into the ReadyNAS) it can only support up to 16 TiB volume size and file sizes up to 2 TiB. So while the individual drives are supported, the volume size that they created was not.

Ext2 (and ext3) do support up to 32TiB if the block size is 8KiB but the problem would be how to make the ReadyNAS set up the file system with this block size. I suspect that one could (using SSH) manually fix an incomplete setup by creating the volume with the larger block size and complete creating the media and backup directories.but that only pushes the limitation a little way down the road and may have all sorts of problems with hot-swapping drives in the event of a failure.

My solution was to buy a diskless ReadyNAS 316 enclosure which uses btrfs and tops out at 16EiB and definitely supports the WD60EFRX drives.

I hope that this post will help other people who may contemplate this experiment themselves.

How my mind thinks about things...

I'm a great believer in the alliance between the subconscious and the conscious minds to solve technical problems. It started at school with an excellent piece of exam advice from a great teacher (Hello Mr Burgess!). 

The advice was to read a paper fully at the start of the exam, see which questions you already knew the answer to and which ones you didn't. 

You then answered the questions that you knew the answer to before re-reading the others where you realised that you knew the many of the answers because your subconscious had worked it out. Rinse and repeat. 

This advice stood me in good stead through many exams though obviously your subconscious couldn't help you out if you hadn't done the work In the first place. 

This led me to read up on the subconscious and work out a number of ways to work with my subconscious successfully. 

My favourite ones to read up and think as fully about a problem as I possibly can one day. Sleep on it and either I will find the answer comes to mind as I wake up or a soon as I start working on the problem again. Sometimes it will take several rounds of sleeps and working on the problem but I almost always arrive at an answer. 

Unfortunately my mind doesn't always differentiate between a problem I need to work on (IT, personal etc.) and something that I just happened to read about. For example the other night I arrived at a theory about the reason why certain galaxies appear heavier than they are why super-massive black holes appeared much earlier than expected in the universe. 

What is interesting is that I remember a chunk of the rather non-linear thought process that generated these ideas. 

I woke up on Thursday morning last week and as I was waking I started thinking about the experience of a being that had lived its entire life in a closed box with no seams or windows and had no way of knowing if there was anything out side the box or if the box was the entirety of existence. I then thought that this was kind of like the experience of us within our own universe. I then went on to think about what else might enter the box to provide evidence of something outside and I realised that gravity was a good bet. Theoretically by constructing some very sensitive instruments the being inside the box could start to infer the existence of things outside the box by mapping the force and direction gravity within the box. 

The first 'Aha!' moment came when I thought about the fact that gravity is thought to be so weak because it leaks out of our 4 dimensions into others and I realised that what leaks out can leak back in!

This then suggested that any unusual unexplained gravitational effects in the wider universe could be as a result of deeper structures leaking gravity back in. 

I remembered the articles that I had read about dark matter and Modified Newtonian Dynamics trying to explain why there is greater mass / gravitation seen in certain galaxies than expected. 

My brain then jumped to a possible explanation. The fact is that we don't know how the 4 dimensions are folded in the wider dimensions so could the gravity in the 4 dimensions be leaking back into those 4 dimensions at a distance? In effect galaxies and other structures should be mutually reinforcing their gravity as it leaks out of the 4 dimensional universe and leaks back in another place. This could explain the excess gravitational attraction seen in certain galaxies and would explain the early appearance of supermassive black holes as a feedback loop caused by matter concentrating in multiple places in the 4 dimensional universe mutually reinforcing itself across the wider dimensions causing more matter to infall. 

Now as I write I'm wondering whether the bigger structures, galactic clusters and voids, are reflective of this effect.

I expect that this has already been thought of by a physicist but this is what my mind does to me some mornings!