diff --git a/WHATS_NEW b/WHATS_NEW index 670522238..5e5af75e5 100644 --- a/WHATS_NEW +++ b/WHATS_NEW @@ -1,5 +1,6 @@ Version 2.01.01 - =================================== + Update vgcreate man page. Version 2.01.00 - 17th January 2005 =================================== diff --git a/man/vgcreate.8 b/man/vgcreate.8 index d1d9b2a03..74655d7a5 100644 --- a/man/vgcreate.8 +++ b/man/vgcreate.8 @@ -33,29 +33,44 @@ previously configured for LVM with .SH OPTIONS See \fBlvm\fP for common options. .TP -.BR \-A ", " \-\-autobackup " {" y | n } -Controls automatic backup of VG metadata after the change (see -.BR vgcfgbackup (8)). -Default is yes. -.TP .BR \-l ", " \-\-maxlogicalvolumes " " \fIMaxLogicalVolumes\fR -Sets the maximum possible logical volume count. -More logical volumes can't be created in this volume group. -Absolute maximum is 256. +Sets the maximum number of logical volumes allowed in this +volume group. +The setting can be changed with \fBvgchange\fP. +For volume groups with metadata in lvm1 format, the limit +and default value is 255. +If the metadata uses lvm2 format, the default value is 0 +which removes this restriction: there is then no limit. .TP .BR \-p ", " \-\-maxphysicalvolumes " " \fIMaxPhysicalVolumes\fR -Sets the maximum possible physical volume count. -More physical volumes can't be included in this volume group. -Absolute maximum is 256. +Sets the maximum number of physical volumes that can belong +to this volume group. +The setting can be changed with \fBvgchange\fP. +For volume groups with metadata in lvm1 format, the limit +and default value is 255. +If the metadata uses lvm2 format, the default value is 0 +which 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--metadatacopies 0\fP +as described in \fBpvcreate(8)\fP. .TP .BR \-s ", " \-\-physicalextentsize " " \fIPhysicalExtentSize\fR[\fBkKmMgGtT\fR] Sets the physical extent size on physical volumes of this volume group. A size suffix (k for kilobytes up to t for terabytes) is optional, megabytes is the default if no suffix is present. Values can be from 8 KB to 16 GB in -powers of 2. The default of 4 MB causes maximum LV sizes of ~256GB because as -many as ~64k extents are supported per LV. In case larger maximum LV sizes are -needed (later), you need to set the PE size to a larger value as well. Later -changes of the PE size in an existing VG are not supported. +powers of 2. The default is 4 MB. +Once this value has been set, it is difficult to change it without recreating +the volume group which would involve backing up and restoring data on any +logical volumes. +If the volume group metadata uses lvm1 format, there is a limit of 65534 +extents in each logical volume, so the default of 4 MB leads to a maximum +logical volume size of around 256GB. +If the volume group metadata uses lvm2 format there is no such restriction, +although having a large number of extents will slow down +the tools but have no impact on I/O performance to the logical volume. +The 2.4 kernel has a limitation of 2TB per block device. .SH EXAMPLES To create a volume group named .B test_vg @@ -67,11 +82,6 @@ with default physical extent size of 4MB: \ vgcreate test_vg /dev/sdk1 /dev/sdl1 .fi -To limit kernel memory usage, there is a limit of 65536 physical extents -(PE) per logical volume, so the PE size determines the maximum logical volume -size. The default PE size of 4MB limits a single logical volume to 256GB (see -the -s option to raise that limit). -There is also (as of Linux 2.4) a kernel limitation of 2TB per block device. .SH SEE ALSO .BR lvm (8), .BR pvdisplay (8),