thayerz00r

I figured something like that would happen, but thanks for the heads up! The idea of oversubscribing space is neat, but I'm not planning on making a habit of doing it. I didn't know about the ls -lsk command line to get the "current/max" though! It's good to know, I was wondering if it was possible. So raw does populate sparsely rather than allocating all the disk space at the time of creation, but unlike qcow2, it shows the total possible used in size rather than "what's been used" if that makes sense. Right now, I've only got 2 vms and plan on adding another SSD/cache drive before adding another machine to the pool. Thanks again for the information!

That's kinda of what it seems like to me, the main window of my unraid setup shows that I'm using 358 gb storage on the cache array, but when I break out the handy calculator, just vdiscs show that i should be using 376... not including everything in the user shares. (which should be upwards of another 125+), so I'm "using" 501 (yay napkin math) but have 140g free of 498. I'd say that a good combination of reflink and symlinks are at work! In layman's terms, looks like it makes a snapshot, and allocates a very little bit of space to hold it's snapshotty goodness... and any changes to that snapshot file actually increase the space used by that snapshot. So VM, 30 gig (doing it with qcow2 saves a ton of space, and I've not seen any performance difference between raw and that... ymmv), get it set up... snapshot a few times, VMStorage1.qcow2, 2, 3, 4... use those in your vms... and you've used like 45 gigs instead of 120 at the start AND your original is intact. *boggles* So, if you're planning on using this for a games library or the like, update the original (or a snapshot for that matter) snapshot again 1234, attach new snapshotted vdiscs to your vms, profit. Still low space usage. Question for any of you gurus out there -- I suppose this doesn't work if the original is on your regular magnet array, does it? It would probably make a copy of the file to the cache and use the space like if the original was deleted... that would just be a-maze-ing if it worked like that

So it looks like it's covered here: (it's in the 7 gamers 1pc video) and replied to by jonp: So it looks to me like, create your vdisk and load it up with stuff and snapshot it using reflink... seems to me to be much like a symlink, but while making a snapshot at the same time.... Interesting

I think it was mentioned in one of the Linus Tech videos. Maybe the 7 VM's in 1 PC. Gary I've been searching for this as well.. it was something like "some trickery with btrfs to save space." Can't seem to find how to do it.. network mapping or symlinking a Steam library works okay from another vm's cached vdisc (though smb sharing from the host's main cache share is slow even with SMB2/3 turned off -- 5-10 sec launches vs 2 min launch). I'll be re-watching those videos again today probably, see if I can get any more detail on it.