Re: bhyve and vfs.zfs.arc_max, and zfs tuning for a hypervisor

2019-03-21 Thread Patrick M. Hausen
Hi all, > Am 21.03.2019 um 11:24 schrieb Matt Churchyard via freebsd-virtualization > : > I'd also be intrigued to know what the logic in FreeNAS is for it. It is > simply a case of "(arc = total_ram - guest_allocated)"? > Is there a lower limit based on a percentage or total RAM, and/or a hard

RE: bhyve and vfs.zfs.arc_max, and zfs tuning for a hypervisor

2019-03-21 Thread Matt Churchyard via freebsd-virtualization
> > > > > 1. Does ARC actually cache zfs volumes (not files/datasets)? > > > > Yes it does. > > I find this distinction between volumes/files/etc and what is cached > causes confusion (as well as "volumes not datasets"). > > Both ZVOLs and Z file systems are types of dataset. A dataset stores

Re: bhyve and vfs.zfs.arc_max, and zfs tuning for a hypervisor

2019-03-20 Thread Victor Sudakov
Matt Churchyard wrote: > > > > > 1. Does ARC actually cache zfs volumes (not files/datasets)? > > > > Yes it does. > > I find this distinction between volumes/files/etc and what is cached > causes confusion (as well as "volumes not datasets"). > > Both ZVOLs and Z file systems are types of

Re: bhyve and vfs.zfs.arc_max, and zfs tuning for a hypervisor

2019-03-20 Thread Mike Gerdts
On Tue, Mar 19, 2019 at 3:07 AM Patrick M. Hausen wrote: > Hi! > > > Am 19.03.2019 um 03:46 schrieb Victor Sudakov : > > 1. Does ARC actually cache zfs volumes (not files/datasets)? > > Yes it does. > > > 2. If ARC does cache volumes, does this cache make sense on a hypervisor, > > because guest

Re: bhyve and vfs.zfs.arc_max, and zfs tuning for a hypervisor

2019-03-20 Thread Patrick M. Hausen
Hi Matt, > Am 20.03.2019 um 10:34 schrieb Matt Churchyard : >>> 2. If ARC does cache volumes, does this cache make sense on a >>> hypervisor, because guest OSes will probably have their own disk cache >>> anyway. >> >> IMHO not much, because the guest OS is relying on the fact that when >> it

Re: bhyve and vfs.zfs.arc_max, and zfs tuning for a hypervisor

2019-03-20 Thread Patrick M. Hausen
Hi! > Am 20.03.2019 um 02:52 schrieb Victor Sudakov : > Is SLOG also used by zfs volumes? Yes, but for synchronous writes only, if I’m not mistaken. So fundamentally yes, but in most cases no. Patrick -- punkt.de GmbH Internet - Dienstleistungen - Beratung Kaiserallee 13a

RE: bhyve and vfs.zfs.arc_max, and zfs tuning for a hypervisor

2019-03-20 Thread Matt Churchyard via freebsd-virtualization
Patrick M. Hausen wrote: > > > 1. Does ARC actually cache zfs volumes (not files/datasets)? > > Yes it does. I find this distinction between volumes/files/etc and what is cached causes confusion (as well as "volumes not datasets"). Both ZVOLs and Z file systems are types of dataset. A dataset

Re: bhyve and vfs.zfs.arc_max, and zfs tuning for a hypervisor

2019-03-19 Thread Victor Sudakov
Patrick M. Hausen wrote: > > > 1. Does ARC actually cache zfs volumes (not files/datasets)? > > Yes it does. > > > 2. If ARC does cache volumes, does this cache make sense on a hypervisor, > > because guest OSes will probably have their own disk cache anyway. > > IMHO not much, because the

Re: bhyve and vfs.zfs.arc_max, and zfs tuning for a hypervisor

2019-03-19 Thread Patrick M. Hausen
Hi! > Am 19.03.2019 um 03:46 schrieb Victor Sudakov : > 1. Does ARC actually cache zfs volumes (not files/datasets)? Yes it does. > 2. If ARC does cache volumes, does this cache make sense on a hypervisor, > because guest OSes will probably have their own disk cache anyway. IMHO not much,

bhyve and vfs.zfs.arc_max, and zfs tuning for a hypervisor

2019-03-18 Thread Victor Sudakov
Dear Colleagues, I have a FreeBSD 11.2 system with 32G RAM which I'm going to use as a bhyve host with zvols and sparse zvols, with (almost) no services/daemons of its own. Could you please clarify some points for me? 1. Does ARC actually cache zfs volumes (not files/datasets)? 2. If ARC does