Home dir as native ZFS filesystem?

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Home dir as native ZFS filesystem?

Postby Sharko » Mon Aug 15, 2016 6:59 pm

So, I'm still at the playing around stage of ZFS at this point. I originally planned to use a ZVOL formatted to HFS+ for my non-admin user home directory (leaving my admin user on a native HFS+ boot volume SSD). I was able to get that to work pretty well, in that OS X El Capitan could point to the proper place for that non-admin user, my files were there when I logged in, all the software ran, etc. However... I ran into a showstopper for that approach. It appears that one can't make snapshots of a ZVOL while it is mounted and live; when I think about it, it makes perfect sense, since ZFS has no visibility into what HFS+ is doing with/to the volume. and it can't know a safe time to take the snapshot. I'm guessing that snapshots work just fine with a native ZFS dataset, since ZFS can choose to do the snapshot at an appropriate moment in between filesystem activity. Have I got that right?

So-o-o, I'm considering discarding the volume approach and just using a native ZFS filesystem dataset for my non-admin user home directory. I've followed the recommendations for creating an HFS+ compatible dataset from the wiki (having to do with case insensitivity, normalization, etc), and I've set the HFS mimic property to ON (I set all that up as pool properties so that they would be inherited by all child datasets).

My question is, how viable is this approach for the whole user directory under El Capitan? Does it step on the toes of SIP? Are there certain applications that don't really play nice unless a real HFS+ filesystem is used? Any listing of pitfalls for this use case would be greatly appreciated. Thanks,

Kurt
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Re: Home dir as native ZFS filesystem?

Postby Brendon » Wed Aug 17, 2016 2:55 am

ZFS homedir is doable. I have personally done it for a couple of years now. You will most likely need to turn the HFS mimic feature on to keep some applications happy. You will need to wait for the pool to be fully imported before attempting to log on. There are reports that iTunes is not all that happy on ZFS, never noticed it myself though.

Your mileage may vary!

Cheers
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Re: Home dir as native ZFS filesystem?

Postby Sharko » Wed Sep 07, 2016 12:17 pm

Just to give an update: I've been running my home dir on a native ZFS dataset without problems for a couple weeks now. I've been using the full functionality of iTunes to update an iPhone and two iPads and an iPod, no incidents. Spotlight seems to work OK at finding files. I don't run Time Machine, as I find it incredibly buggy and annoying even on an HFS+ volume. About the only precaution that I take in my daily routine is to give the disks about 10 seconds to spin up when logging in after an awaken from sleep.

So, I would give it a tentative thumbs-up as my daily driver.

Kurt
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Re: Home dir as native ZFS filesystem?

Postby zisper » Wed Sep 14, 2016 4:04 pm

I'm running a native ZFS home directory (with HFS mimic, and no atime), and I've been playing around with Sierra. One thing that I've noticed is that it's not playing nicely with iCloud documents. Seems to be almost constantly updating them, and it does not like at all if I edit documents on another device (either iOS or web interface) whilst the Sierra machine is running. (If I only open/edit files on the Sierra machine it seems to work ok, aside from the updating.) I can be editing a file on the web interface and I'll get a notification that the Sierra machine has deleted the document.
I'm wondering if it's related to atime, or something else - I haven't had the time to really investigate what's causing the issues yet. (It may not even be related to ZFS, but given Sierra is due for imminent release, I expect it is - I haven't seen any complaints of similar issues to mine in forums.)
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Re: Home dir as native ZFS filesystem?

Postby Brendon » Wed Sep 14, 2016 8:17 pm

Probably a bit premature to be running O3X on Sierra! As written elsewhere we know it somewhat works but have not reached a point where we think it is stable.

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Re: Home dir as native ZFS filesystem?

Postby zisper » Thu Sep 15, 2016 1:20 pm

Oh, I'm not relying on it under Sierra - just playing with it when I get the chance. :)
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Re: Home dir as native ZFS filesystem?

Postby Brendon » Thu Sep 15, 2016 3:44 pm

I might add that I am note sure we have ever played well with iCloud document synchronization. Its not a feature I use, and I recall some discussion of this in the past.

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Re: Home dir as native ZFS filesystem?

Postby Sigmoid » Mon Feb 20, 2017 5:13 am

Well I've been doing this for some time back on Yosemite, and now recently went back to it on Sierra. The big catch is, never try to log on without making sure the filesystem is mounted, otherwise you'll be in a world of pain. Back on Yosemite I've had permanent corruption of my user settings due to a premature logon...

As I just posted in the general discussion forum, LaunchPad doesn't seem to like having ~/Applications on ZFS. Otherwise, no issues so far. There used to be an iTunes lock issue that would cause iTune to hang for ten-twenty minutes at a time, but I haven't experienced that recently, only some sluggishness time to time, especially when importing, downloading or updating a lot of stuff at a time.
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Re: Home dir as native ZFS filesystem?

Postby Sharko » Tue Feb 21, 2017 3:00 pm

I'm still on 1.5.2 of openzfsonosx, running El Capitan, so my observations may not correspond to what you get with Sierra/1.6.x. What I've observed is that deleting files in a ZFS home directory is the slowest operation. If I have a lot of files in the trash, and execute Empty Trash from the Finder, then things thrash along for a while (but eventually complete just fine). I see some slowdowns in iTunes once in a while, but again I think it is related to file deletion being a bit slow.

When I first set up my home dir on the ZFS filesystem dataset, all the shortcuts in the left hand pane of a Finder window still went back to the non-ZFS (HFS+) volume that originally had my home directory (before I copied the home directory onto the ZFS dataset). I had to delete all those shortcuts, and create new ones from the ZFS home directory; then things worked fine.

I don't think I had to do anything with the Applications link, either in the Finder window or the dock, to have that work, unlike the problem you reported in a different thread.
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