- Add Q2 entry on ZFS TRIM
Submitted by: smh
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2020-12-08 03:00:23 +00:00
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1 changed files with 59 additions and 1 deletions
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@ -18,7 +18,7 @@
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<!-- XXX: keep updating the number of entries -->
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<p>Thanks to all the reporters for the excellent work! This report
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contains 11 entries and we hope you enjoy reading it.</p>
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contains 12 entries and we hope you enjoy reading it.</p>
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<!-- XXX: set date for the next set of submissions -->
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<p>The deadline for submissions covering between July and September 2013
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@ -548,4 +548,62 @@
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yet supported.</p>
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</body>
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</project>
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<project cat='kern'>
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<title>ZFS TRIM and Enhanced <tt>BIO_DELETE</tt> Support</title>
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<contact>
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<person>
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<name>
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<given>Pawel Jakub</given>
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<common>Dawidek</common>
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</name>
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<email>pjd@FreeBSD.org</email>
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</person>
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<person>
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<name>
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<given>Steven</given>
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<common>Hartland</common>
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</name>
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<email>smh@FreeBSD.org</email>
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</person>
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</contact>
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<body>
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<p>As of the end of June, &os;'s ZFS implementation now includes
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TRIM support in <tt>head</tt>, <tt>stable/9</tt>, and
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<tt>stable/8</tt> branches. This allows ZFS to help maintain
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high performance on flash-based devices such as SSD's even under
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high-load conditions.</p>
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<p>When creating new pools and adding new devices to existing
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pools it first performs a full-device level TRIM to help ensure
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optimum starting performance. This behaviour can be overridden
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by setting the <tt>vfs.zfs.vdev.trim_on_init</tt> sysctl
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variable to <tt>0</tt> if for example the disks are new or have
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already been secure erased, which can also now be done using
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<tt>camcontrol(8)</tt> security actions.</p>
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<p>In order to support TRIM, the kernel requires the underlying
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device driver supports <tt>BIO_DELETE</tt>. This is currently
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mapped through to hardware methods such as ATA TRIM and SCSI
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UNMAP, which are commonly supported by SSDs via CAM.</p>
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<p>In order to increase the supported hardware base, CAM's SCSI
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layer was also enhanced to allow ATA TRIM via SATL ATA
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Passthrough to be used in addition to the existing UNMAP and WS
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methods. This allows SATA disks attached to SCSI controllers
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with CAM based drivers such as <tt>mps(4)</tt> and
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<tt>mpt(4)</tt> to provide delete support.</p>
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<p>Stats for ZFS TRIM can be monitored by looking at the sysctl
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variables under <tt>kstat.zfs.misc.zio_trim</tt> in addition to
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live GEOM delete stats via the <tt>gstat -d</tt> command.</p>
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<p>This project was sponsored by <a
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href="http://www.multiplay.com">Multiplay</a> and implemented by
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Pawel Jakub Dawidek.</p>
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</body>
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</project>
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</report>
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