Where are my iSCSI drives and can I use "dd" or some CLI to back them up?

[knucklehead42]

I have set up a RAIDz1 zpool with 4 iSCSI zvol "drives" that I can attach to my Windows 10 desktop, each of 2 Win 10 laptops, and to my Linux machine.
From the command line I can not find the iSCSI "drives" (eventually I want to back up to an LTO tape drive) and have not figured out how to see what is on each "drive" save from the machine that has attached the "drive". The GUI indicates that storage space is being used, but so much is hidden, and my old school bones rattle and get nervous when I can't SEE for myself in a convenient way that doesn't require me going to another part of the house and commandeering my wife's laptop or desktop...
So, where are the iSCSI zvol/"drives" that I can see from the command line? Or from the GUI? The zpool containing the iSCSI only shows the "jails" directory... I know they are in there somewhere, but this old schooler can't seem to locate them, even with "find / -iname bigmama", for example...

 

[zambanini]

you can not. since your box only provides a raw volume to the client, the client also takes care about the filesystem,

 

[garm]

As the previous post said, you cannot mount the zvol, your windows machines handle the filesystem over iSCSI. Are you aware you the limitations of using iSCSI? Are there any perticular reason you cannot use straight up network shares?

If you stick with zvol’s, just backup the dataset where you created the them recursively and your set. Zvol’s aren’t files or folders, they are datasets. You “find” them by running the zfs command. zfs is really helpful and you can build almost any report you want, but if you just want a list of all your datasets with the default statistics run zfs list

 

[knucklehead42]

As the previous post said, you cannot mount the zvol, your windows machines handle the filesystem over iSCSI. Are you aware you the limitations of using iSCSI? Are there any perticular reason you cannot use straight up network shares?

I understand I can not mount the zvol in FreeNAS, just in the "client" machines, but should it not show up as a lump of space when a FreeNAS command like
"ls -Al /mnt/zpoolxyz"
is issued? I have an LTO (SAS) tape drive that I want to back the whole thing up to, but I need to see what is there before I go down that path...

If you stick with zvol’s, just backup the dataset where you created the them recursively and your set. Zvol’s aren’t files or folders, they are datasets. You “find” them by running the zfs command. zfs is really helpful and you can build almost any report you want, but if you just want a list of all your datasets with the default statistics run zfs list

Thanks... That led me on a path of discovery... there is enough similarity between Unix, Linux, and FreeBSD/FreeNAS that I can grasp the commands, but I am now wondering at the efficacy of using a tape to backup the zpool, set as RAIDz1, to bare metal.

 

[danb35]

should it not show up as a lump of space when a FreeNAS command like "ls -Al /mnt/zpoolxyz" is issued?

No, because ls lists files, and a zvol isn't a file. It isn't a directory. It isn't part of the filesystem in any way. And though I'm not certain, I doubt you'll be able to back one up to tape.

 

[knucklehead42]

No, because ls lists files, and a zvol isn't a file. It isn't a directory. It isn't part of the filesystem in any way. And though I'm not certain, I doubt you'll be able to back one up to tape.

Danb, I believe you are correct... clearly the data is there somewhere, because I can see it from the machines linked to the iSCSI drives, and the
zfs list
shows storage used...
Sadly, most of what I have learned about computers, operating systems, file systems, databases, media, etc. has been through trial and error, beginning with a hybrid vacuum tube/discrete transistor computer 60 years ago and growing in several directions.
I guess I wish I had known more about how ZFS manages everything - I have read loads of material, but until I smacked into the wall, it had not dawned on me that an old school tape backup was not likely to work.
Back to the learning (drawing) board...