Date: Thu, 21 Mar 2019 00:30:45 +0100 From: "Patrick M. Hausen" <hausen@punkt.de> To: Matt Churchyard <matt.churchyard@userve.net> Cc: Victor Sudakov <vas@mpeks.tomsk.su>, "freebsd-virtualization@freebsd.org" <freebsd-virtualization@freebsd.org> Subject: Re: bhyve and vfs.zfs.arc_max, and zfs tuning for a hypervisor Message-ID: <B02887DA-D1B8-48A8-8F4B-C02A02F0726A@punkt.de> In-Reply-To: <6388ebd5a12949179ff6da33eb107205@SERVER.ad.usd-group.com> References: <20190319024638.GA8193@admin.sibptus.ru> <AA997A20-4EBF-46DF-A517-FD2072682545@punkt.de> <20190320015236.GA35511@admin.sibptus.ru> <6388ebd5a12949179ff6da33eb107205@SERVER.ad.usd-group.com>
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Hi Matt, > Am 20.03.2019 um 10:34 schrieb Matt Churchyard = <matt.churchyard@userve.net>: >>> 2. If ARC does cache volumes, does this cache make sense on a=20 >>> hypervisor, because guest OSes will probably have their own disk = cache anyway. >>=20 >> IMHO not much, because the guest OS is relying on the fact that when=20= >> it writes it=E2=80=99s own cached data out to =E2=80=9Edisk=E2=80=9C, = it will be committed to=20 >> stable storage. >=20 > Maybe I've missed something but I don't quite get the link between = read cache (ARC) and guest writes here? You are correct - I confused ARC and ZIL. I still recommend to set sync=3Dalways for hypervisor =E2=80=9Edisk=E2=80=9C ZVOLs. Kind regards Patrick --=20 punkt.de GmbH Internet - Dienstleistungen - Beratung Kaiserallee 13a Tel.: 0721 9109-0 Fax: -100 76133 Karlsruhe info@punkt.de http://punkt.de AG Mannheim 108285 Gf: Juergen Egeling
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