svn commit: r42125 - head/en_US.ISO8859-1/htdocs/news/status

Wed Jul 3 07:15:30 UTC 2013

Author: pgj
Date: Wed Jul  3 07:15:29 2013
New Revision: 42125
URL: http://svnweb.freebsd.org/changeset/doc/42125

Log:
  - Add Q2 entry on ZFS TRIM
  
  Submitted by:	smh

Modified:
  head/en_US.ISO8859-1/htdocs/news/status/report-2013-04-2013-06.xml

Modified: head/en_US.ISO8859-1/htdocs/news/status/report-2013-04-2013-06.xml
==============================================================================

--- head/en_US.ISO8859-1/htdocs/news/status/report-2013-04-2013-06.xml	Wed Jul  3 07:02:33 2013	(r42124)
+++ head/en_US.ISO8859-1/htdocs/news/status/report-2013-04-2013-06.xml	Wed Jul  3 07:15:29 2013	(r42125)
@@ -18,7 +18,7 @@
 
     <!-- XXX: keep updating the number of entries -->
     <p>Thanks to all the reporters for the excellent work!  This report
-      contains 11 entries and we hope you enjoy reading it.</p>
+      contains 12 entries and we hope you enjoy reading it.</p>
 
     <!-- XXX: set date for the next set of submissions -->
     <p>The deadline for submissions covering between July and September 2013
@@ -548,4 +548,62 @@
 	yet supported.</p>
     </body>
   </project>
+
+  <project cat='kern'>
+    <title>ZFS TRIM and Enhanced <tt>BIO_DELETE</tt> Support</title>
+
+    <contact>
+      <person>
+	<name>
+	  <given>Pawel Jakub</given>
+	  <common>Dawidek</common>
+	</name>
+	<email>pjd at FreeBSD.org</email>
+      </person>
+
+      <person>
+	<name>
+	  <given>Steven</given>
+	  <common>Hartland</common>
+	</name>
+	<email>smh at FreeBSD.org</email>
+      </person>
+    </contact>
+
+    <body>
+      <p>As of the end of June, &os;'s ZFS implementation now includes
+	TRIM support in <tt>head</tt>, <tt>stable/9</tt>, and
+	<tt>stable/8</tt> branches.  This allows ZFS to help maintain
+	high performance on flash-based devices such as SSD's even under
+	high-load conditions.</p>
+
+      <p>When creating new pools and adding new devices to existing
+	pools it first performs a full-device level TRIM to help ensure
+	optimum starting performance.  This behaviour can be overridden
+	by setting the <tt>vfs.zfs.vdev.trim_on_init</tt> sysctl
+	variable to <tt>0</tt> if for example the disks are new or have
+	already been secure erased, which can also now be done using
+	<tt>camcontrol(8)</tt> security actions.</p>
+
+      <p>In order to support TRIM, the kernel requires the underlying
+	device driver supports <tt>BIO_DELETE</tt>.  This is currently
+	mapped through to hardware methods such as ATA TRIM and SCSI
+	UNMAP, which are commonly supported by SSDs via CAM.</p>
+
+      <p>In order to increase the supported hardware base, CAM's SCSI
+	layer was also enhanced to allow ATA TRIM via SATL ATA
+	Passthrough to be used in addition to the existing UNMAP and WS
+	methods.  This allows SATA disks attached to SCSI controllers
+	with CAM based drivers such as <tt>mps(4)</tt> and
+	<tt>mpt(4)</tt> to provide delete support.</p>
+
+      <p>Stats for ZFS TRIM can be monitored by looking at the sysctl
+	variables under <tt>kstat.zfs.misc.zio_trim</tt> in addition to
+	live GEOM delete stats via the <tt>gstat -d</tt> command.</p>
+
+      <p>This project was sponsored by <a
+	  href="http://www.multiplay.com">Multiplay</a> and implemented by
+	Pawel Jakub Dawidek.</p>
+    </body>
+  </project>
 </report>
