question about DFS

[latrosicarius]

Hi, i was wondering if anyone using DFS could tell me if this is possible.

Say I have two hard drives. I want to combine them into one logical drive which can be shared on the network. I do not want to use RAID or JBOD.

If I combine them using DFS, can they be separated at a later time and accessed from a different computer like normal slave drives? Will their respective files be intact as separate drives, or do they rely on each other?

Thanks

[Moby-Dick]

I don't think DFS is what you want ? it wont really 'combine' drives per se.

best you could do is create a DFS root and have it replicate data between the drives but it sounds like you are not wanting to mirror data ?

[latrosicarius]

Moby, that is correct. I will have separate drives for backup purposes.

All I want is to find a way of combining drives into a single virtual volume that does not permanently link the drives into an array so that they cannot be separated at a later date.

I am currently using RAID, which i do not like because it is not portable. For instance, I cannot simply unplug one of those RAIDed drives from the array and slap it into a different computer and get the files off of it.

I understand when dealing with combined drives that I would not be able to get off all the files if I only had one drive from the array, but I at least want a setup where I would be able to get whole (intact) files.

[Moby-Dick]

I think I understand what you want. ( being able to do it is another matter however )

did you know you can present a drive as a folder ? ie have 1 file share with 2 folders ( 1 for each drive )

[Steve]

Yes, I was going to suggest the same thing as Moby - mount one of the drives as a folder in the within "main" drive. The files remain on their respective drives (no mirroring, no striping, nothing) but as far ask accessing the files goes, they're all under the same drive letter.

[Syllopsium]

I am currently using RAID, which i do not like because it is not portable. For instance, I cannot simply unplug one of those RAIDed drives from the array and slap it into a different computer and get the files off of it.

Yes you can, otherwise your RAID isn't up to much.

It may have to be a highly similar computer and feature various limitations depending on the RAID you're using, but absolutely it should be possible to remove enough of the RAID array to reconstitute it on another computer.

What are you actually trying to do? Create a mostly synchronised set of hard drives that can be put in any computer or removed at a moment's notice?

PK

[latrosicarius]

Syllopsium, my goal is to be able to take any drive from the array and plug it into a completely different computer, and access it as a stand-alone slave drive without re-RAIDing it. I have been using RAID5 for years and I do not believe RAID can do that.

PeteSmith, I don't know much about JBOD. Do you think it works in the way I am talking about?

Moby, Steve, thanks. That sounds like it could work if I can't find another solution.

[PeteSmith]

In my mind JBOD would do exactly what you want. It would consolidate two hard drives into 1 virtual drive. If at a later date you wanted to remove one of the drives you could do so and still access all the data stored on it. You won't be able to choose which drive the data is stored on however. JBOD is not actually raid, even though it is often classified as such.

[Syllopsium]

Syllopsium, my goal is to be able to take any drive from the array and plug it into a completely different computer, and access it as a stand-alone slave drive without re-RAIDing it. I have been using RAID5 for years and I do not believe RAID can do that.

Depends on the level of RAID. For RAID level 1 (mirroring), you can take a drive out and plug it into a different computer as the data is only spread across two hard drives.

RAID 5 distributes the data over at least three disks, so you'd need to remove at least two of them, and the array won't be in operation whilst you're doing so.

Even so, *why* do you want to do that? It'd be much better to write data to a backup tape/drive or have a backup tape/drive/server which is constantly updating itself from the master copy. Removing and reinserting RAID disks isn't something to be done, except in an emergency. Resilience isn't backup.

Your best option if you must go down the route, is probably to insert a second disk at a certain point in the directory tree on your fileshare, but then of course you lose out on resilience.

Is your intention to provide as much network storage as possible whilst spending no extra money? Obviously SATA disks are extremely cheap these days, and even SAS isn't that pricey.

PK

[pipTheGeek]

I'm not sure that DFS is what you need, but it could do exactly as you want. BUT. It will only present the two drives as subfolders under a common share. It won't do anything to change how the local machine views the discs, nor will it actually merge the drives. You could equally well just create two different shares on the one PC. I'm not sure how much advantage DFS would give in this situation.

[latrosicarius]

Thanks all. I think I'll research a bit into the portability of JBOD. I guess DFS is not what I thought it was. Worst case, I'll just share each drive separately.

Syllopsium, I don't think I can explain why I don't want RAID any more than I have already done. I already am using RAID5 like I mentioned previously and I am well aware of its capabilities and limitations. You ask me why, but I've already said the reason I want to drop RAID it is for portability on generic hardware.

Also, RAID 1 does not solve any problem. Yes, each drive is just a copy so all files on it are completely intact and thus the drive would be individually portable to other systems. However, RAID 1 does not provide combined space, which is what I'm looking for.

Like I mentioned to Moby, I do have separate drives for backup purposes so RAID 1 would provide me with no advantage except for increased uptime assurance if one drive were to fail. I am not a company so I really don't mind downtime.

Thanks

[MaddAussie]

Have you thought of using synctoy?

http://www.microsoft.com/downloads/d...displaylang=en

It will allow you to sync the data between the two drives

[mikerr]

In my mind JBOD would do exactly what you want. It would consolidate two hard drives into 1 virtual drive. If at a later date you wanted to remove one of the drives you could do so and still access all the data stored on it. You won't be able to choose which drive the data is stored on however. JBOD is not actually raid, even though it is often classified as such.

Have you actually seen any JBOD implementaton be capable of that ?
I haven't - JBOD is usually just able to have different sized disks presented as one volume.
Lose one, and you lose the whole volume. A single disk doesn't have any recognizable filesystem on it.

JBOD isn't RAID in the same way as RAID0 isn't really RAID - no (R)edundancy.
But they are all loosely grouped as RAID has become to mean "a group of disks presented as a volume".

I think the OP wants a single volume to show 2 drive contents.

E.g. F:\drive1 and F:\drive2

This can be done with "NTFS junctions"
http://en.wikipedia.org/wiki/NTFS_junction_point

[latrosicarius]

mikerr, I think you hit on my fear of JBOD and why I originally didn't want to use it. I believe it might be possible for JBOD disks to be individually portable, but I have yet to see a real-world implementation of RAID hardware or software that does not simply span all the disks into a single array, thus making the individual drives unrecognizable if you were to try to take them out of the array and plug one into another computer as a slave drive.

I think pieces of SAMBA could be used to create a daemon that will do exactly what I want.

Namely, the administrator will supply config file that contains a list of arbitrary directories that you wish to be shared. The daemon will will simply represent them (and all their subdirectories) as a single merged directory tree when serving out folder listings to windows clients via SMB.

It would not actually merge anything, and NTFS permissions would still be persisted, as it would check the requester's network credentials and compare it to the security permissions of each file or folder he requests to be listed/accessed.

[mikerr]

If all PCs accessing it are post-vista (including over the network) you can use symbolic links:
http://en.wikipedia.org/wiki/NTFS_symbolic_link

[12GaugeShotty]

Thanks all. I think I'll research a bit into the portability of JBOD. I guess DFS is not what I thought it was. Worst case, I'll just share each drive separately.

Syllopsium, I don't think I can explain why I don't want RAID any more than I have already done. I already am using RAID5 like I mentioned previously and I am well aware of its capabilities and limitations. You ask me why, but I've already said the reason I want to drop RAID it is for portability on generic hardware.

Also, RAID 1 does not solve any problem. Yes, each drive is just a copy so all files on it are completely intact and thus the drive would be individually portable to other systems. However, RAID 1 does not provide combined space, which is what I'm looking for.

Like I mentioned to Moby, I do have separate drives for backup purposes so RAID 1 would provide me with no advantage except for increased uptime assurance if one drive were to fail. I am not a company so I really don't mind downtime.

Thanks

DFS is best used so that everything appears from one server even though files might be stored across several servers. You also need a Windows Server OS, which you haven't stated whether you have or not.