Peristant UnionFS?

[reub2000]

Instead if using the RAM disc as part of the UnionFS file system, why not use a persistant hard drive partition. Combined with a persistant home, you could create a poor mans instalation, which acted like a real instalation. Would this be possible?

[andrewmuck]

Was looking through to see if someone has already done it. Puppy linux seems to write files into extra session tracks. I was thinking it would be good to either write to usb prior to shutdown, or really nifty would be to write to the disc (assume rw media, or just append extra session like puppy)

There have been several times when I have had to power down and would have liked to keep /ramdisk

I suppose this could be done manually, just the times I needed to was hard pressed for time. I intend to pursue this, although for what I want the hard disk is not an option, and usb's are a bit small, hence the thought of tacking on an encrypted backup of the ramdisk to the end of the dvd.

If anyone has already done this for knoppix I'd like to know.


cya, Andrew...

[[email protected]]

You can do it after the fact. Here is what I did to expand my /UNIONFS in knoppix. I mounted a free partition at /mnt/sda1, then did a "unionctl /UNIONFS --list" to make sure I know the top priority part of the union, then a --add to stick the new partition on top. df shows I now have plenty of elbow room in UNIONFS. Whether this is persistent or not is another question.

mount bla bla bla

df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/root 2471 19 2452 1% /
/ramdisk 808568 662484 146084 82% /ramdisk
/UNIONFS 2750524 2604440 146084 95% /UNIONFS
/dev/sda2 1035692 741788 241292 76% /cdrom
/dev/cloop 1941958 1941958 0 100% /KNOPPIX
/UNIONFS/dev/sda4 150689348 25805684 117229096 19% /homey
/UNIONFS/dev/sda1 1035660 33176 949876 4% /mnt/sda1


unionctl /UNIONFS --list
/ramdisk (rw)
/KNOPPIX (r-)


unionctl /UNIONFS --add --before /ramdisk --mode rw /mnt/sda1

df -h
Filesystem Size Used Avail Use% Mounted on
/dev/root 2.5M 19K 2.4M 1% /
/ramdisk 790M 647M 143M 82% /ramdisk
/UNIONFS 3.7G 2.6G 1.1G 71% /UNIONFS
/dev/sda2 1012M 725M 236M 76% /cdrom
/dev/cloop 1.9G 1.9G 0 100% /KNOPPIX
/UNIONFS/dev/sda4 144G 25G 112G 19% /homey
/UNIONFS/dev/sda1 1012M 33M 928M 4% /mnt/sda1

web pages I found helpful:
http://www.unionfs.org/
http://www.fsl.cs.sunysb.edu/project-unionfs.html
http://www.knoppix.net/wiki/Trivial_...ion_filesystem

this may also be of interest - combine unionfs & gmailfs for true mobility:
http://www.knoppix.net/wiki/Gmailfs

[cintra]

Instead if using the RAM disc as part of the UnionFS file system, why not use a persistant hard drive partition. Combined with a persistant home, you could create a poor mans instalation, which acted like a real instalation. Would this be possible?

Sounds like Slax's 'changes=/dev/device' cheatcode mode..

I suggested they take a look at it on the Kanotix forum, but there was little response..

It allows me to have a Poormans Install to a /slax folder somewhere (e.g. hdb16) and a Linux 'changes' partition (hdb17 in my case). On top of that I boot with 'copy2ram', so the result is exceedingly fast, both booting and in use, AND changes are automatically taken care of.

Mvh

[[email protected]]

I was overly optimistic - UNIONFS let me add the hard drive, but still acted like it was out of space when the ram part filled up. I'm guessing that it needs to be added earlier in the process, or better yet, instead of the ramdisk. Sounds like major surgery to me.

[malaire]

I was overly optimistic - UNIONFS let me add the hard drive, but still acted like it was out of space when the ram part filled up. I'm guessing that it needs to be added earlier in the process, or better yet, instead of the ramdisk. Sounds like major surgery to me.

You can use

sudo unionctl /UNIONFS --mode /ramdisk ro

to make ramdisk-branch readonly. After that no additional data will be written to it. You should of course add another read-write branch before doing this.

[firnsy]

I was overly optimistic - UNIONFS let me add the hard drive, but still acted like it was out of space when the ram part filled up. I'm guessing that it needs to be added earlier in the process, or better yet, instead of the ramdisk. Sounds like major surgery to me.

It would only require a few changes in the miniroot.gz, primarily the mounting of /ramdisk. Instead of configuring a tmpfs filesystem and then mounting that on /ramdisk you could take a real disk and mount it on /ramdisk. This would then of course, as described above, give you your persistant RAM.

[probono]

See the unionrw= cheatcode in Kanotix. (Don't know whether Knoppix has this by now, too...)
http://kanotix.com/PNphpBB2-viewtopic-t-6846.html

[starlyptErin_.]

UNIONFS? ...that is, yes I can do the above and set up a separate partition, BUT HOW DO I SET UP THAT PARTITION on a thumb drive?

[starlyptErin_.]

...it doesn't appear to exist, and how do i add an additional unionfs partition to another partition..?