Date: Thu, 19 May 2016 10:00:13 -0600 From: Alan Somers <asomers@freebsd.org> To: Adrian Chadd <adrian.chadd@gmail.com> Cc: "Kenneth D. Merry" <ken@freebsd.org>, Bruce Simpson <bms@fastmail.net>, "src-committers@freebsd.org" <src-committers@freebsd.org>, "svn-src-all@freebsd.org" <svn-src-all@freebsd.org>, "svn-src-head@freebsd.org" <svn-src-head@freebsd.org> Subject: Re: svn commit: r300207 - in head: sbin/camcontrol sys/cam/ata sys/cam/scsi sys/dev/ahci sys/geom sys/geom/eli sys/kern sys/sys usr.sbin usr.sbin/diskinfo usr.sbin/zonectl Message-ID: <CAOtMX2gBUDAp-CFU9nKyAaHL99UMh-yJyzkhvHWA1JXSJAB3OA@mail.gmail.com> In-Reply-To: <CAJ-VmonddYfrWjqb3%2B%2B9bJ2sj1pcDLrfCRxKP223XdQE7tOSLw@mail.gmail.com> References: <201605191408.u4JE8aPL079390@repo.freebsd.org> <573DCE0D.70400@fastmail.net> <20160519145033.GA69089@mithlond.kdm.org> <CAJ-VmonddYfrWjqb3%2B%2B9bJ2sj1pcDLrfCRxKP223XdQE7tOSLw@mail.gmail.com>
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On Thu, May 19, 2016 at 9:54 AM, Adrian Chadd <adrian.chadd@gmail.com> wrote: > On 19 May 2016 at 07:50, Kenneth D. Merry <ken@freebsd.org> wrote: > > On Thu, May 19, 2016 at 15:30:37 +0100, Bruce Simpson wrote: > >> Right On Commander! > >> > >> Now here is hoping the random-write issues with OpenZFS are solved... > > > > Well, this is of course only the underlying infrastructure for SMR > drives. > > > > As for the random write issues with ZFS (or rather sequential I/O going > out > > in random order), we (Spectra) are working on that in general. > > > > The original plan was to do full SMR support for ZFS, but it looks like > we > > may get good enough write performance with Drive Managed drives by just > > making writes from ZFS to drives more sequential rather than going for > full > > Host Aware and Host Managed support. If that turns out that performance > > isn't good enough after all, then we'll have to put in the effort to put > > Host Aware support at least into ZFS. > > > > That's why I said (in the commit message) that I don't know of anyone > > working on using the SMR infrastructure for UFS or ZFS. Now that the > > plumbing is in place in CAM and GEOM, it is possible at the filesystem > > level if someone wants to do the work. > > Is it possible to use this from userland for now? Ie, probe whatever > we need to in order to understand the transaction geometries (ie, the > optimal sizes for reading/writing, etc) and then issue IOs that are in > line with this? > > > > -adrian > > Sure. You can do all that with zonectl or its ioctls, if you have a userland program that writes to raw block devices. Reset Write Pointer is supported, too. -Alan
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