DSM-G600, DNS-3xx and NSA-220 Hack Forum

random404 · 2011-10-17 16:40:35

The popular thread on this forum at http://dns323.kood.org/forum/viewtopic.php?id=1150 says "Automatically copying all data from one drive to the other can be used as part of a backup strategy. Some reports indicate that RAID1 is not altogether reliable, so this may be a better alternative. I have all my working data on Volume_1 and rotate backup disks in Volume_2, every month." This is exactly what I'd like to do, and I was very happy to read that thread because earlier I posted on the dlink forum (at the thread http://forums.dlink.com/index.php?topic=41639.0, which I've pasted below) about the same thing and was told it isn't possible. Please allow me to explain:

I currently have 2 drives in the DNS 323 (I do not use RAID), and only use the first drive (HD_a2) when modifying/accessing things. Periodically, I will back up HD_a2 to the 2nd drive (HD_b2) by using rsync. So HD_b2 operates solely as a backup of HD_a2.

What I'd like to do is backup HD_a2 to a 3rd and maybe even 4th drive periodically using rsyncl. I tried using the USB slot, and it worked for a while but has lately become very unreliable for me with transfers crashing every few minutes and needing to be restarted (some combination of the DNS 323, the USB cable, or the USB enclosure is messing things up) - bottom line, I don't want to use the DNS 323's USB slot anymore.

What I imagine is removing HD_b2, putting in a new drive in its place, and then copying the data from HD_a2 to HD_b2 (subsequent transfers would then use rsync instead of the cp command). Then remove that 3rd drive, put the original HD_b2 back in its place. The idea would be every few weeks to swap the 3rd drive with the 2nd drive (both in the spot of HD_b2) and update it with the latest contents of HD_a2. I vaguely remember trying something like this a long time ago but remember it not being possible - I think the DNS 323 was asking me to format EVERYTHING on the 3rd drive when I put it back into the 2nd bay a few weeks after the initial transfer in order to update the data on it from HD_a2...which, if I have remembered this correctly, is terribly lame.

Of course I'll back up all my data before trying any of your suggestions, but could you tell me if what I envision is possible with the DNS 323 (I really hope so otherwise I'm not sure I can continue using the DNS 323 if I can't regularly and easily make additional backups as I wish)? Could anyone give me detailed steps of how to go about doing it the right way? Thanks so much, I really appreciate your help.

However, I was advised that it wouldn't be possible:

Secondly, the DNS-323 assigns a unique identifier to the HDD in each slot, which my very well force a reformat when you swap in an "unknown" HDD.

And this was my response:

I've gotta say, the DNS 323 is very frustrating with this 'unique identifier' - it has come up for me before as well. It's unbelievable that I cannot put in a new drive without being prompted to reformat it - particularly because I'm not even using RAID! The DNS is unnecessarily treating the 2 drives as a 'pair' rather than what they really are - 2 independent drives. Unless I've misunderstood something here, I don't know what purpose it serves - I'm dumbfounded by this design.

The way I see it a NAS should be like any other computer - if I have a desktop with 2 separate drives in it, I can copy data from drive A to drive B, then replace drive B with drive C and then back to drive B and keep everything in sync. So if I'm understanding this correctly, the DNS 323 does not operate in this sensible manner?

Now is there REALLY no way to use the DNS 323 itself to keep other drives in sync with its contents without using some form of USB enclosure (either connected to the DNS 323 or to a computer on the network)? Had I known I would certainly have opted for another solution rather than purchasing a DNS 323.

If anyone could please comment on this and let me know whether there's any hope of me accomplishing what I'd like to, that would be much appreciated. I realize the thread on this forum says it's possible, but I just thought I'd double-check because I got conflicting information from the other forum. But I'm wondering, is the way described in that thread a reliable way to do it, or is it 'hack-ish' and error-prone? Anyway, if it is possible to do what I've described above then I've just developed a newfound appreciation for my DNS 323 Thank you so much.

FunFiler · 2011-10-17 17:19:33

This has been discussed many times.

NAS units like this one are not designed for repeated insertion/extraction. Nor are the HDDs for that matter. Will it work? Yes, at least short term. There are MANY different options, most of which are better than swapping internal drives.

karlrado · 2011-10-17 22:00:42

I use the rsync (actually rsnapshot) and multiple B drive method. I swap B disks about every three months. This has been working fine for a couple of years and I intend to continue as long as things last.

While it is wise to not insert/extract disks too often, I don't see anything wrong with a few times a year. The DNS-323 enclosure seems to make taking disks in and out easy without requiring tools. So I doubt that the design would start failing after an absurdly low number of cycles.

As far as the unwanted formatting goes, it has been awhile since I formatted my second B disk. If I remember right, I probably went the safe route. I removed both my A and B disks from the enclosure and put my new B disk in. I let it reformat the new B disk. If my data is on a couple of disks sitting on the desk, the DNS-323 can't reformat them. Then I put in the A disk and the new B disk and made sure it booted without reformatting, etc. Then let things sync up and I was in business.

random404 · 2011-10-17 22:32:25

Thanks for the response karlrado - I have a couple of questions for you. When you say B disk, what do you mean? Do you mean the Volume_2, aka the drive in the LHS bay?

Also, out of curiosity why have you chosen to go with the multiple drive swapping option, rather than using a USB drive attached to the DNS 323?

And finally, when you format your 'second B disk', do you put it in the LHS or RHS drive bay?

Thanks!

karlrado · 2011-10-18 01:50:30

Disk A is Volume_1 and is in the right hand slot, as you face the machine from the front.

Disk B is Volume_2 and is in the left hand slot, as you face the machine from the front.

Some people call them A and B because the mount points are /mnt/HD_a? and /mnt/HD_b? and the device names are /dev/sda and /dev/sdb.

The Volume_1 and Volume_2 names are just the Samba default export names. Internal backup programs like rsync aren't going to know the drives by the samba names, so I tend to use the other names in this context.

When I formatted the new B drive, I really don't remember which slot I put it in. I forget what happens if you just install one drive in the LHS. I would just try it and see.

I'm not using a USB drive to back up the NAS for a couple of reasons. I don't have and do not want a USB drive that is large enough. External USB drives also mean more cables and possibly power supplies that have to be plugged in and powered on all the time. I'm using the USB port on the back to attach a printer. I know I can get a USB hub, but I simply have not; that's more cables, clutter and perhaps power supplies. I was going for a low power, low clutter config.

DSM-G600, DNS-3xx and NSA-220 Hack Forum

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#1 2011-10-17 16:40:35

Very CONFUSED about if it's possible to rotate backup (LHS) drives?

#2 2011-10-17 17:19:33

Re: Very CONFUSED about if it's possible to rotate backup (LHS) drives?

#3 2011-10-17 22:00:42

Re: Very CONFUSED about if it's possible to rotate backup (LHS) drives?

#4 2011-10-17 22:32:25

Re: Very CONFUSED about if it's possible to rotate backup (LHS) drives?

#5 2011-10-18 01:50:30

Re: Very CONFUSED about if it's possible to rotate backup (LHS) drives?

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