Is there any way to set up a software RAID..? Please help.

[jonahnaylor]

Hi, I think I may be asking the impossible but I wanted to double check before I try swapping my hardware etc as I've spent a lot of wasted time messing about trying to set it all up.

Is there a way to create a USB raid on a JBOD enclosure with the readynas nv+??

Please if anyone can help me set this up it would mean a lot. I have bought an Icy Box model: http://www.amazon.co.uk/Icy-Box-Ib-3221stu-b-Aluminium-Technology/dp/B001AIBHEO/ref=cm_cr_pr_pb_t

This is plugged in VIA usb to my ready nas+, with the intention of it serving as a backup drive. It has 2 x 2tb drives.

My ready nas has 4 x 1tb drives in which are all in RAID mode to give me 4tb.

My problem is my back up drive just shows 2x 2tb drives and there is no way to set it up as a raid on the enclosure to be a 4tb drive... It's just a JBOD so shows the drives up individually...

Does anyone know of a way to use a software raid setup on the Readynas, maybe set it up with the console or an addon so I can make my usb backup drive mirror the Readynas in capacity?

Thanks for any help or advice.

[macmouse]

Short Version: Technically, it probably can be done but no it will not be easy and definitely will be far from "point and click".

If you don't like the mess with the guts of things, than you can just re-organize your file structure so that you can fit roughly half in each folder and run a separate backup script for each drive. You could also pay the extra money and get a model that has built-in hardware RAID.

Long Version:
It is very likely that your device would become *unsupported* as a result of this process. Unless you are a linux veteran I wouldn't risk it IMHO or at least be willing to risk screwing things up and loosing your data (but hey, it's a great learning opportunity ^_^ )

If you still want to do it, here is a few hints to get you started

First - You have to enable root and SSH access in order to be able to dig into the command line
http://www.readynas.com/?p=4203

Then you want to follow the software RAID howto and format partitions on the USB.
http://tldp.org/HOWTO/Software-RAID-HOWTO.html

The readers digest of the process on a normal linux computer
1) Partition each drive to the software RAID format (one big partition is fine)
2)edit /etc/raidtab and put them into a raid that you are looking for (in this case, RAID0)
Looks like you will need to find an example online and copy it as it appears to be empty on my model.
3)run raidstart and cross your fingers

**Warnings**
-RAID0 has *zero* redundancy and if either drive in the pair dies for any reason than your screwed and loose the data. You can do the other types of RAID as well, the guide explains everything you need to know. If this is only a backup of the existing data on the NAS than it shouldn't be that big of a deal.

-ReadyNas has their own proprietary software when it comes to the raid so this /shouldn't/ mess things up as this is running independently but I don't know where they hook into the system so it might not work or even screw stuff up. (Lawyer mode) - Don't blame me if you end up bricking it. You are doing this at your own risk,etc,etc.

-According to the logs, RAID auto-detection is disabled in the kernel at startup. So you will probably have to login and tell it to start the raid each time it boots unless you are willing to mess with the boot-loader to change the kernel arguments.

-It will run like crap and there is no way around it.
On a SPARC based unit it would be excruciatingly painful due to various USB IO limitations. It might run a bit better on a x86 based unit, but it will still be very slow compared to the built-in drives because of the tremendous USB overhead. Still, if this is only for backup than speed might not be a priority for you and as long as it is automated you don't have to worry about it.

As you can see, I've seriously thought about doing what you are doing what you are trying to do. However, I decided against it because it's very risky, requires a large amount of work and will perform very poorly, all of which essentially defeats the whole point of getting a readynas in the first place.

[jonahnaylor]

THANK YOU so much for your detailed answer. It seems to not be worth it and instead i'll take your advice and instead create two backup policies to split the data over two drives roughly. It's not perfect but the alternatives seems a lot of work. Thanks again for your answer and help.

[Scaevola]

Hmmm.

That brings up another Scenario. You probably could set up a jbod raid but you would need some low level os running on it like freenas which is a freeware software based raid array system. So you would need a small computer and run a usb - usb between the computer.

I have been running raid 0 arrays on computers since 2001 on IDE (oh yeahhhh) ata66 & ata100. It was substantial increase(and a pain-in-the-butt to reformat) [windows install disks do not come raid drives ...naturally...and they MUST be loaded via a 3.5 inch disk. Windows 7 was the first os I've seen that included them.

In the last 12 years I've had raids go offline 4 times. 2 times it came back and 2 times I lost everything(And yes it sucks!).

If you are going to cheap route that's probably what I do if you are trying to increase the storage on your nas box without using xraid to increase the size(or it it's maxed) but the usb connections are write protected so you would need to transfer all the content to the array and then connect it up.

[macmouse]

I know there is USB enclosures out there that do true hardware raid inside.

I.E. you put in 2-4 drives in the box, flip a couple of dip switches (or run a software app on a laptop to set it up). After that, you plug it into any computer and it shows up as a single USB hard disk without requiring any drives/setup.

It's tricky a bit to make sure they are truly hardware, because a lot of them require you to install software on windows which then does pretend software raid but they are out there. Sadly, they start around $200 (plus drives) and rise pretty quickly from there and you could find a ReadyNAS duo on sale for ~$200.

[gwing]

Caveat: I've only ordered my ReadNas today so know nothin about its own software, but doing what you want independently using standard Linux facilities ought to be quite easy - if you want to go to the trouble. I magine the biggest difficulty might be 'hiding' your USB disks from the RN software so it doesn't try to use them itself. OTOH this might be easy - I just don't know the proprietary software yet.

Anyway to provide one big vol from two in the usb rack you have two ways (probably more).
1) As sugested before use software raid. Simply look aty the devices and see your two usb devces, then use one of the unix raid too;ls (I like mdadm) to create a raid volume from this. Now you see 3 devices, the two originals plus the raid device of their combined size (if you choose raid 0). Then simply use this new device like you would any other i.e. craete a file system on it and then export it or publish to windows with samba or do whatever you like with it. It may even be possible to use this combined device with the RN software but I wouldn't know about that.
2) Use LVM. Just create a volume group and assign both physical devices to it. Then create a single logical volume using the whole space in the volume group i.e. both drives. Then use that new logical volume the same way you would with the above raid volume or any other system volume i.e. create file system and export etc.
The second option is probably the easiest and most flexible. Note that both are only really suitable if you can both get the RN software from interfering with them and you are going to leave them permanently connected, they are not hotplug solutions.

[macmouse]

The flash memory that contains the "master" copy of the OS (at least on the sparc based units) is very small. I believe it is around 256MB.

As a result, a lot of packages/files that are a part of a standard linux distribution are not included because they are not necessary as it is expected everything will be managed through their web interface. So you can't properly make any assumptions that certain commands/libraries will be there unless you have a live system to verify what is included.

Also, a lot of packages are modified to make them smaller than usual (for example, there is no man pages). It is possible that you can change the apt repository to point to a debian mirror and download newer version of packages (such as it is, because the readynas [at least on sparc] is based on sarge where package updates have long been discontinued) but there is risk that you will download a package that can break compatibility.


I specifically remember reading postings where people who upgraded enough packages and it effectively bricked their unit (stopped booting). I can't remember off the top of my head, but I thought there was a few config files that are in non-standard locations.

I know the RAIDX is a combination of LVM and hardware raid. I have plugged in a readynas drive into a standard linux box and was able to mount the OS partition (which is a small RAID1 partition that is mirrored across all disks). I can't remember whether I was able to read the main dataset or not.

-I wasn't aware you could split a partition across two drives that way (JBOD style) using LVM. You might be able to make it work, but I would careful about mixing up the built-in stuff (although you could mitigate the risk by trying it out before populating any data).