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NAS | Backup Use

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September 22, 2012 4:44:34 PM

I want to clarify some things about using my NAS for backup use (my other thread kind of wandered off topic):

1. I think I understand the trivial case of file backup - you just throw files on the NAS harddrives, backup done (the file system doesn't matter so long as you read/recover said files using the NAS itself (or if the NAS hardware has failed, you buy another NAS, or in my case since the file system is ext4 - I should be able to attach the (non-RAID) HDDs to a linux machine and read them.


2. I am confused however, as to the case of saving an image of my Windows Machines on the NAS for backup purposes.

I want to image the Windows7 OS drive, save that image to the NAS, AND have a program which does incremental backup - save those files to the NAS as well. Ordinarily, this would be simple. In this case though, I have the NTFS/ext4 problem since the NAS cannot be told to use NTFS file systems.

Now I haven't gone through the process of testing it in vivo, but I'm wondering whether or not this will prove to be a problem - when my OS dies, and I go to the NAS to get my image and restore it, will Windows be able to 'read' the image file off of the NAS Ext4 file system?

3. If not - would I be able to add a 2nd step - and transfer said image file, with backup files, to a USB external (or some other media) which IS formatted to NTFS, and then use THAT to restore the system?

(I understand the temptation to simply say 'use an external USB drive to begin with, but my usage setups make using the NAS a bit more useful to me, as I have a large number of discrete machines)

Thanks

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September 23, 2012 5:12:44 AM

If you create an image, and back it up to the NAS, it is stored onto the NAS as a file. If you are using Windows Backup, you restore it from that file once you have reinstalled Windows. The NAS should have no issues with restoring the file, so long as nothing on the NAS itself gets corrupted (or the drive fails).

Formatting of the drive only matters if you were to remove the drive and stick it into another system.
a c 85 G Storage
September 23, 2012 5:40:03 AM

commissarmo said:
I want to clarify some things about using my NAS for backup use (my other thread kind of wandered off topic):

1. I think I understand the trivial case of file backup - you just throw files on the NAS harddrives, backup done (the file system doesn't matter so long as you read/recover said files using the NAS itself (or if the NAS hardware has failed, you buy another NAS, or in my case since the file system is ext4 - I should be able to attach the (non-RAID) HDDs to a linux machine and read them.


2. I am confused however, as to the case of saving an image of my Windows Machines on the NAS for backup purposes.

I want to image the Windows7 OS drive, save that image to the NAS, AND have a program which does incremental backup - save those files to the NAS as well. Ordinarily, this would be simple. In this case though, I have the NTFS/ext4 problem since the NAS cannot be told to use NTFS file systems.

Now I haven't gone through the process of testing it in vivo, but I'm wondering whether or not this will prove to be a problem - when my OS dies, and I go to the NAS to get my image and restore it, will Windows be able to 'read' the image file off of the NAS Ext4 file system?

3. If not - would I be able to add a 2nd step - and transfer said image file, with backup files, to a USB external (or some other media) which IS formatted to NTFS, and then use THAT to restore the system?

(I understand the temptation to simply say 'use an external USB drive to begin with, but my usage setups make using the NAS a bit more useful to me, as I have a large number of discrete machines)

Thanks


When you create a backup of a filesystem the backup is almost always encapsulated in an image format. The entire filesystem is dumped as a binary blob into a file on the filesystem that is going to store the backup. The only limitation here is that the destination filesystem must be able to handle the size of the backup in a single file, fortunately all major OS-level filesystems can handle massive files.

I will caution you though that NAS drives can be extremely slow. Any NAS drive that has appreciable IO throughput will also be very expensive (often upwards of $500 just for the unit itself). I eventually ditched my NAS for an external RAID enclosure which is so fast that it actually saturates a 3Gb/s eSATA link
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September 26, 2012 7:15:18 PM

Thanks for the replies.

1. How is your external RAID enclosure different from an NAS - just the fact that you don't connect it via ethernet, but use eSATA? - how does that work viz. RAID controller?

2. Presumably then - it's all right if I backup my OS image to my NAS then, and then simply restore that image file (regardless of file system) when I require it?


a c 85 G Storage
September 26, 2012 8:46:01 PM

commissarmo said:
Thanks for the replies.

1. How is your external RAID enclosure different from an NAS - just the fact that you don't connect it via ethernet, but use eSATA? - how does that work viz. RAID controller?

2. Presumably then - it's all right if I backup my OS image to my NAS then, and then simply restore that image file (regardless of file system) when I require it?


1. The RAID enclosure is like an external hardware RAID card, it's much much faster than a NAS. The RAID controller is internal to the RAID enclosure. It simply shows up as a volume to the OS. Some RAID enclosures may expose SMART data or other SATA management commands.

2. Yes that would work fine, but backing an entire image up to a NAS will take a lot longer than it will to an external RAID enclosure.
September 27, 2012 3:27:52 PM

Ah ok - I should have looked into that more carefully.

I've since realized - an external RAID enclosure is basically just an NAS without the network card or onboard mini-OS. i.e. An NAS is an external RAID enclosure that is also network capable rather than just DAS.

So anyone with an NAS could also (provided there's eSATA/USB/etc) connectivity - just direct connect it and use it as an 'external RAID enclosure,' though since NAS are generally more expensive, this probably would only be done with something one already owns.
a c 85 G Storage
September 27, 2012 4:21:17 PM

commissarmo said:
Ah ok - I should have looked into that more carefully.

I've since realized - an external RAID enclosure is basically just an NAS without the network card or onboard mini-OS. i.e. An NAS is an external RAID enclosure that is also network capable rather than just DAS.

So anyone with an NAS could also (provided there's eSATA/USB/etc) connectivity - just direct connect it and use it as an 'external RAID enclosure,' though since NAS are generally more expensive, this probably would only be done with something one already owns.


Yeah sort of. NAS generally hide the storage controller behind a weak ARM or Atom processor that serves up the data over HTTP or NFS. They can't be connected via eSATA because that would violate the NAS OS's exclusive lock on the storage controller. Some interfaces such as SAS would work in this fashion but not SATA. It's not technically impossible but it would involve installing an eSATA interface between the NAS processor and the eSATA port that attempts to make the processor transparent, a real solution in search of a problem.
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