From 8d959b6c75a6cc98691413ec4eab5b01e992d6c1 Mon Sep 17 00:00:00 2001 From: Heinz Mauelshagen Date: Thu, 28 Jul 2016 17:34:42 +0200 Subject: [PATCH] man: lvcreate correction on --stripes explanation and examples with respect to the changed, configurable default behaviour introduced with commit 7eb79091937d. E.g. raid default of 2 stripes rather than number of PVs in the VG or on the command line minus one. --- man/lvcreate.8.in | 29 +++++++++++++++++++++-------- 1 file changed, 21 insertions(+), 8 deletions(-) diff --git a/man/lvcreate.8.in b/man/lvcreate.8.in index 1cce0b6ae..34b652367 100644 --- a/man/lvcreate.8.in +++ b/man/lvcreate.8.in @@ -603,14 +603,24 @@ for online conversion to thin volumes with external origin. .br Gives the number of stripes. This is equal to the number of physical volumes to scatter -the logical volume. When creating a RAID 4/5/6 logical volume, +the logical volume data. When creating a RAID 4/5/6 logical volume, the extra devices which are necessary for parity are internally accounted for. Specifying \fB\-i 3\fP -would use 3 devices for striped logical volumes, -4 devices for RAID 4/5, and 5 devices for RAID 6. Alternatively, -RAID 4/5/6 will stripe across all PVs in the volume group or -all of the PVs specified if the \fB\-i\fP -argument is omitted. +would cause 3 devices for striped and RAID 0 logical volumes, +4 devices for RAID 4/5, 5 devices for RAID 6 and 6 devices for RAID 10. +Alternatively, RAID 0 will stripe across 2 devices, +RAID 4/5 across 3 PVs, RAID 6 across 5 PVs and RAID 10 across +4 PVs in the volume group if the \fB\-i\fP argument is omitted. +In order to stripe across all PVs of the VG if the \fB\-i\fP argument is +omitted, set raid_stripe_all_devices=1 in the allocation +section of \fBlvm.conf (5)\fP or add +.br +\fB\-\-config allocation/raid_stripe_all_devices=1\fP +.br +to the command. +.br +Note the current limitation of 8 stripes total in any RaidLV including parity devices. + Two implementations of basic striping are available in the kernel. The original device-mapper implementation is the default and should normally be used. The alternative implementation using MD, available @@ -801,9 +811,12 @@ a parity drive for a total of 4 devices) and a stripesize of 64KiB: .B lvcreate \-\-type raid5 \-L 5G \-i 3 \-I 64 \-n my_lv vg00 Creates a RAID5 logical volume "vg00/my_lv", using all of the free -space in the VG and spanning all the PVs in the VG: +space in the VG and spanning all the PVs in the VG (note that the command +will fail if there's more than 8 PVs in the VG in which case \fB\-i 7\fP +has to be used to get to the currently possible maximum of +8 devices including parity for RaidLVs): .sp -.B lvcreate \-\-type raid5 \-l 100%FREE \-n my_lv vg00 +.B lvcreate \-\-config allocation/raid_stripe_all_devices=1 \-\-type raid5 \-l 100%FREE \-n my_lv vg00 Creates a 5GiB RAID10 logical volume "vg00/my_lv", with 2 stripes on 2 2-way mirrors. Note that the \fB-i\fP and \fB-m\fP arguments behave -- 2.43.5