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From: wysochanski@sourceware.org To: lvm-devel@redhat.com, lvm2-cvs@sourceware.org Subject: LVM2/man vgchange.8.in Date: Mon, 28 Jun 2010 20:36:00 -0000 [thread overview] Message-ID: <20100628203618.17341.qmail@sourceware.org> (raw) CVSROOT: /cvs/lvm2 Module name: LVM2 Changes by: wysochanski@sourceware.org 2010-06-28 20:36:18 Modified files: man : vgchange.8.in Log message: Define vgmetadatacopies in vgchange man page. This patch adds a vgmetadatacopies parameter for metadata balancing. This parameter provides a simple way for users to create a policy for placing metadata on PVs automatically by LVM. The behavior is implemented inside LVM by managing the 'ignore' mda bits. We chose the name 'vgmetadatacopies' as this is a natural extension to the existing parameter 'pvmetadatacopies' / 'metadatacopies' in pvcreate. This is a first step at VG parameter based metadata balancing. Most users will probably want to state that they want a certain number of PVs to contain metadata, and they may be less concerned about a specific number of metadata copies in the volume group. However, for default values (pvmetadatacopies is 1 by default), the number of metadatacopies in the volume group, and the number of PVs with metadata are the same. In the future we could add vgmetadatacopiespvs to define more specifically the number of pvs in the VG that contain metadata, but for now we start with this parameter. Another possible future extension would be to define a specific pv tag to mark the set of PVs that should be used for metadata balancing. This tag based approach could be used in conjunction with 'vgmetadatacopies'. Signed-off-by: Dave Wysochanski <dwysocha@redhat.com> Patches: http://sourceware.org/cgi-bin/cvsweb.cgi/LVM2/man/vgchange.8.in.diff?cvsroot=lvm2&r1=1.9&r2=1.10 --- LVM2/man/vgchange.8.in 2010/05/06 11:15:55 1.9 +++ LVM2/man/vgchange.8.in 2010/06/28 20:36:18 1.10 @@ -25,6 +25,8 @@ .IR MaxLogicalVolumes ] .RB [ -p | \-\-maxphysicalvolumes .IR MaxPhysicalVolumes ] +.RB [ \-\-[vg]metadatacopies ] +.IR NumberOfCopies|unmanaged|all ] .RB [ \-P | \-\-partial] .RB [ \-s | \-\-physicalextentsize .IR PhysicalExtentSize [ \fBbBsSkKmMgGtTpPeE\fR ]] @@ -127,13 +129,23 @@ Changes the maximum number of physical volumes that can belong to this volume group. For volume groups with metadata in lvm1 format, the limit is 255. -If the metadata uses lvm2 format, the value 0 -removes this restriction: there is then no limit. -If you have a large number of physical volumes in -a volume group with metadata in lvm2 format, -for tool performance reasons, you should consider -some use of \fB--pvmetadatacopies 0\fP -as described in \fBpvcreate(8)\fP. +If the metadata uses lvm2 format, the value 0 removes this restriction: +there is then no limit. If you have a large number of physical volumes in +a volume group with metadata in lvm2 format, for tool performance reasons, +you should consider some use of \fB--pvmetadatacopies 0\fP as described in +\fBpvcreate(8)\fP, and/or use \fB--vgmetadatacopies\fP. +.TP +.BR \-\-vgmetadatacopies " " \fINumberOfCopies|unmanaged|all\fP +Sets the desired number of metadata copies in the volume group. If set to +a non-zero value, LVM will automatically manage the 'metadataignore' +flags on the physical volumes (see \fBpvchange --metadataignore\fP) in order +to achieve \fINumberOfCopies\fP copies of metadata. If set to \fIunmanaged\fP, +LVM will not automatically manage the 'metadataignore' flags. If set to +\fIall\fP, LVM will first clear all of the 'metadataignore' flags on all +metadata areas in the volume group, then set the value to \fIunmanaged\fP. +The \fBvgmetadatacopies\fP option is useful for volume groups containing +large numbers of physical volumes with metadata as it may be used to +minimize metadata read and write overhead. .TP .BR \-s ", " \-\-physicalextentsize " " \fIPhysicalExtentSize\fR[\fBbBsSkKmMgGtTpPeE\fR] Changes the physical extent size on physical volumes of this volume group.
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