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Unfortunately no one can be told what fun_plug is - you have to see it for yourself.

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#1 2007-07-05 10:05:18

ldomaigne
Member
Registered: 2007-06-24
Posts: 28

backup strategy for the DNS-323

Hello everybody,

I have currently my DNS-323 running in a RAID-1 configuration. I plan to have valuable data on this storage, like the family picture etc. I would be extremely upset to loose them. Since the RAID-1 implementation is yet sub-optimal, and since the firmware upgrade can bring the array down, there is currently a need to backup the DNS-323.

I see 3 options to that aim:

1)  Use the RAID-1 mirror capability.

Normally, cloning a drive is easy in RAID-1. You just pull out of one the drive, put the brand new disk in the array, and let the mirroring happen. Could this approach be taken to backup the DNS-323, or is there some existing shortcomings with the current 1.03 FW?

By the way, if I erase the partitiion table of a disk, will it then be recognized by the DNS-323 as a new disk to be formatted/mirrored?

2) Use an external disk connected to a Linux system

The idea would be to mount the Volume_1 and copy all the content to an external disk connected to a Linux system via USB for instance. Could be perhaps messy if the Linux system and the DNS-323 use different locale for the filenames encoding?

3) Same as 2), but using the USB port available on the DNS-323

The idea would be to use the fun_plug and to load the appropriate USB kernel module. So that you attach directly an USB drive (or a SATA drive with an USB enclosure) to the DNS-323, and copy the content of Volume_1 to that external drive.

For sure, I will toy a bit. But it would be useful to have your take on those ideas! 

Cheers,
Loïc.

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#2 2007-07-05 10:33:39

DNS-323 Talker
Member
Registered: 2007-05-21
Posts: 245

Re: backup strategy for the DNS-323

Option 1, RAID1, really isn't a backup solution.  For example, file deletions that occur on the first drive are replicated to the second. 

I use option 4 - I back up from the DNS-323 to another external drive in a USB enclosure, which is attached to one of my Windows PCs.  For various reasons unique to my personal setup, option 3, backing up to a disk on the USB port of the DNS-323, isn't an option for me.  If it was, I'd do that.


DNS-323 w/two Seagate 500 GB RAID1
Fonz's Fun_Plug- Don't DNS-323 without it!

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#3 2007-07-05 12:03:19

Emacs
Member
Registered: 2007-06-24
Posts: 110

Re: backup strategy for the DNS-323

Break the mirror (= two individual disks).
Then add a cronjob that dd's the first disk to the 2nd disk every x days.

This is what I plan to do.
Last night I did a first test with dd -if /dev/sda2 -of /dev/sdb2
I ran the dd command while in the ramdisk provided by fonz (used originally for a clean e2fsck with unmounted disks).
It took rather long - some hours for 160GB disks, but I haven't played with the blocksize yet. Maybe this can be optimized.

Hopefully I have some time tonight or tomorrow to remove sda2 from the dns-323, put sdb2 into the first slot and successfully boot the whole thing.


Is this works, I have found my personally preferred solution.

Cheers,

Emacs

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#4 2007-07-05 12:58:04

ldomaigne
Member
Registered: 2007-06-24
Posts: 28

Re: backup strategy for the DNS-323

Hi Emacs,

Emacs wrote:

Break the mirror (= two individual disks).
Then add a cronjob that dd's the first disk to the 2nd disk every x days.

That's also another way to get a sort of mirroring / backup. But I would rather use a smart copy than a dd: only files whose md5sum has changed would be copied to the second disk... (don't know however if such a script can be easily implemented on the DNS-323).

In any case, let us informed about your progress.

Cheers,
Loïc.

P.S> My favorite editor, BTW ;-)

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#5 2007-07-05 13:27:57

fonz
Member / Developer
From: Berlin
Registered: 2007-02-06
Posts: 1716
Website

Re: backup strategy for the DNS-323

ldomaigne wrote:

But I would rather use a smart copy than a dd: only files whose md5sum has changed would be copied to the second disk... (don't know however if such a script can be easily implemented on the DNS-323).

rsync can do this (-c option). I'm not sure, though, if it will perform better than the full copy on this slow processor.

Another interesting feature of rsync is the "hardlink to files in DIR when unchanged" feature (--link-dest option). I think it allows to store several full backups using only disk space for one full backup plus differences (i.e. changed files).

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#6 2007-07-05 14:08:15

frodo
Member
From: Stockholm, Sweden
Registered: 2007-01-17
Posts: 259

Re: backup strategy for the DNS-323

To follow up on fonz proposal. If you install a chroot debian you can easily use rsnapshot.
It uses rsync and maintains multiple "snapshots" of your data. It is possible to customize it fairly much as to how many snapshots and so.

Combining this with an external drive makes it possible to retrieve several versions of a file incase of possible corruption or accidental removal. The good news is that it only copies what has changed and will be relativly fast after the first initial copy.

More info could be found here:

http://www.rsnapshot.org/

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#7 2007-07-06 22:35:44

osxtasy
Member
Registered: 2007-01-29
Posts: 9

Re: backup strategy for the DNS-323

I just backup to a WD500gig usb MYBOOK overnight every couple weeks, or once a month. I wanted to try the fun_plug stuff, but I dont understand linux and how to load it into the DNS323. I asked for help, but I think I'm just a little too stupid to understand what they were trying to explain to me, so I just do it the simple way... Hopefully Dlink or someone will actually make the funplug an actual part of the firmware, and I can then just plug the 500gig Mybook directly into the DNS323 and copy that way. Oh well...

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#8 2007-07-07 13:26:45

Emacs
Member
Registered: 2007-06-24
Posts: 110

Re: backup strategy for the DNS-323

I did some tests with dd'ing the discs and it doesn't seem to bee to good a solution.
Since dd copies the whole disc or partition I got some double shares on the dns-323 afterwards.
My original share was suddenly on the 2nd drive (no real problem, but not expected).

So I will look a bit more into the rsnapshot and rsync options...

Cheers,

Emacs

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