Date: Thu, 26 Mar 2020 10:17:20 -0400 From: mike tancsa <mike@sentex.net> To: Gary Palmer <gpalmer@freebsd.org> Cc: Attila Nagy <bra@fsn.hu>, freebsd-fs@freebsd.org Subject: Re: Importing a vdev copied zpool from file Message-ID: <d721df7f-fa80-e7d4-a5b2-7a5aacbf552b@sentex.net> In-Reply-To: <20200326140739.GB98069@in-addr.com> References: <CAM2hQG_iREkW=tsX=rF8XCOe1CFxumbftr7am6uZ0X6u-YFKQw@mail.gmail.com> <616f6969-b137-7db6-894f-f7612e67abcd@sentex.net> <20200326140739.GB98069@in-addr.com>
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On 3/26/2020 10:07 AM, Gary Palmer wrote: > What if you add the step >> mdconfig *-o async*??-t vnode -f /data/da0 >> >> and then try the import ? Note, the async option adds a pretty big speed >> increase > At least on 11.3, that option has this caveat in the man page: > > -o [no]option > Set or reset options. > > [no]async > For vnode backed devices: avoid IO_SYNC for increased > performance but at the risk of deadlocking the entire > kernel. > > Not sure if the risk of deadlocking the kernel is still there or if it's > worth any potential speedup Its quite a difference in speed. I have been using it for a while on RELENG_12 without any deadlocks while virtualizing servers. On large imports, it would give close to a 50% speedup ---Mike
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