Compression and beachballs... Configuration tips?

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Compression and beachballs... Configuration tips?

Postby DanielSmedegaardBuus » Thu Aug 28, 2014 11:21 pm

Hi :)

I've been using zfsonlinux on my server for what seems like ages now, and when I discovered lately that TimeMachine didn't consider a completely reformatted and repopulated 100GB image file as having changed, and thus not backing it up, I started to think about alternatives. What comes to mind immediately is of course ZFS, and so I was immensely happy to see that ZEVO was no longer the only feasible option. OpenZFS on OS X had appeared! Very beautiful.

One thing, though, that I'm having a bit of trouble with, is the performance of it. (Also a few lock ups that force me to hard reset my laptop, but let's not go there right now).

Since I'm using it for backup, and I'm backing up to an external USB2 drive, I've opted for gzip-9 compression, since it's slow, yes, but more efficient than any other current compression option, and the USB2 bottleneck would theoretically trump my CPU bottleneck — this is a MacBook Air 2013, i7, 8GB RAM, 500 GB SSD.

Okay, so here's the deal. I'm doing my backups with rsync. Specifically,

Code: Select all
nice sudo rsync -avxc --delete --exclude-from=/Users/daniel/.rsync-backup-exclusions / /Backup/Air/


I added the nice part to alleviate the problem, but it doesn't seem to help. The problem is beachballs galore, and massive system lockups (nothing responding for up to 30 seconds) while running this. It seems to get worse over time (memory related?), and particularly bad when backing up large files (such as VMware disk files).

It seems also that it may bring ZFS into some sort of funk, as twice I've tried unmounting and ejecting my ZFS USB drive to sort of "clean the slate", and ended up with hanging zpool and zfs commands until a reboot (which may or may not have required hard rebooting).

Any ideas about this?

Oh, btw, I'm on Yosemite beta, this might very well be very relevant!

EDIT: This does seem very much related to writes rather than reads. I'm currently doing -avxc rsync over an existing backup, which means reading the entire ZFS data before writing anything, and while UI performance is definitely suffering (much more than expected), I see no beachballs, and no lockups per se. Only lagging text input and slow screen updates. And, of course, the fan noise ;)
Last edited by DanielSmedegaardBuus on Thu Aug 28, 2014 11:32 pm, edited 1 time in total.
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Re: Compression and beachballs... Configuration tips?

Postby ilovezfs » Thu Aug 28, 2014 11:25 pm

Have you followed the instructions here?

https://openzfsonosx.org/wiki/Performance
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Re: Compression and beachballs... Configuration tips?

Postby DanielSmedegaardBuus » Thu Aug 28, 2014 11:34 pm

ilovezfs wrote:Have you followed the instructions here?

https://openzfsonosx.org/wiki/Performance


Well, I've read that, if that's what you mean, but there aren't any instructions. What do you mean?
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Re: Compression and beachballs... Configuration tips?

Postby lundman » Thu Aug 28, 2014 11:43 pm

and just to double check, you are running 1.3.0, the latest ?
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Re: Compression and beachballs... Configuration tips?

Postby DanielSmedegaardBuus » Thu Aug 28, 2014 11:59 pm

lundman wrote:and just to double check, you are running 1.3.0, the latest ?


That's right :)
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Re: Compression and beachballs... Configuration tips?

Postby ilovezfs » Fri Aug 29, 2014 12:14 am

DanielSmedegaardBuus wrote:Well, I've read that, if that's what you mean, but there aren't any instructions. What do you mean?


Code: Select all
sudo sysctl -w zfs.arc_max=<arc size in bytes>


Raising arc max should help your performance.
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Re: Compression and beachballs... Configuration tips?

Postby DanielSmedegaardBuus » Fri Aug 29, 2014 12:19 am

ilovezfs wrote:
DanielSmedegaardBuus wrote:Well, I've read that, if that's what you mean, but there aren't any instructions. What do you mean?


Code: Select all
sudo sysctl -w zfs.arc_max=<arc size in bytes>


Raising arc max should help your performance.


Worth a shot, thanks. What would you recommend here? (8GB) How much have you allocated?

Also, if the default (auto-configured) results in this behavior, then I should probably file a bug, no?
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Re: Compression and beachballs... Configuration tips?

Postby ilovezfs » Fri Aug 29, 2014 12:29 am

DanielSmedegaardBuus wrote:Worth a shot, thanks. What would you recommend here? (8GB) How much have you allocated?

I wouldn't go over about (8)(0.75/1.4) ≈ 4.3 GB.

DanielSmedegaardBuus wrote:Also, if the default (auto-configured) results in this behavior, then I should probably file a bug, no?

No. The default is deliberately conservative.
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Re: Compression and beachballs... Configuration tips?

Postby DanielSmedegaardBuus » Fri Aug 29, 2014 12:51 am

ilovezfs wrote:
DanielSmedegaardBuus wrote:Worth a shot, thanks. What would you recommend here? (8GB) How much have you allocated?

I wouldn't go over about (8)(0.75/1.4) ≈ 4.3 GB.


Alright. I see the automatically configured settings put it at around 1.5G ATM.

ilovezfs wrote:
DanielSmedegaardBuus wrote:Also, if the default (auto-configured) results in this behavior, then I should probably file a bug, no?

No. The default is deliberately conservative.


But surely this can't possible be the intended behavior...? It renders it mostly unusable. I mean, I'm using zfsonlinux on my Ubuntu server, 19*2TB RAIDZ3, SSD cached, also 8GB. It behaves nothing like this. And on my Mac it's juggling just a single-drive 500GB pool?

I remember using ZFS-FUSE back in the days, and it had similar effects on GUI experience. Got better over releases. AFAICT, O3X isn't FUSE based, is it?
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Re: Compression and beachballs... Configuration tips?

Postby ilovezfs » Fri Aug 29, 2014 1:00 am

No it's a kernel extension. Are you making a suggestion?
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