[lvm-devel] master - man: add more info/examples to lvmraid(7)
Heinz Mauelshagen
heinzm at sourceware.org
Fri Mar 10 21:40:55 UTC 2017
Gitweb: https://sourceware.org/git/?p=lvm2.git;a=commitdiff;h=164d4a309ca62eb6e7810b76e5616074656258e3
Commit: 164d4a309ca62eb6e7810b76e5616074656258e3
Parent: 15682270f4557958d5e2994990534b652229857d
Author: Heinz Mauelshagen <heinzm at redhat.com>
AuthorDate: Fri Mar 10 22:40:22 2017 +0100
Committer: Heinz Mauelshagen <heinzm at redhat.com>
CommitterDate: Fri Mar 10 22:40:22 2017 +0100
man: add more info/examples to lvmraid(7)
Add a warning about maximum supported numbers of stripes
with striped LVs realtive to RAID conversions.
Add examples for a more elaborate, multi-step conversion
from linear to striped (and vice versa).
Shrink lvs examples output.
Related: rhbz834579
Related: rhbz1191935
Related: rhbz1191978
---
man/lvmraid.7.in | 231 +++++++++++++++++++++++++++++++++++++++++++++---------
1 files changed, 195 insertions(+), 36 deletions(-)
diff --git a/man/lvmraid.7.in b/man/lvmraid.7.in
index 79e6fe0..e5a2dc5 100644
--- a/man/lvmraid.7.in
+++ b/man/lvmraid.7.in
@@ -862,13 +862,66 @@ new parity blocks. Synchronization can take a long time and degrade
performance (rate controls also apply to conversion, see
\fB\-\-maxrecoveryrate\fP.)
+Warning: though it is possible to create \fBstriped\fP LVs with up to 128 stripes,
+a maximum of 64 stripes can be converted to \fBraid0\fP, 63 to \fBraid4/5\fP and
+62 to \fBraid6\fP because of the added parity SubLVs.
+A \fBstriped\fP LV with a maximum of 32 stripes can be converted to \fBraid10\fP.
+
.P
The following takeover conversions are currently possible:
.br
.IP \(bu 3
+between striped and raid0.
+.IP \(bu 3
between linear and raid1.
.IP \(bu 3
+between mirror and raid1.
+.IP \(bu 3
+between 2-legged raid1 and raid4/5.
+.IP \(bu 3
+between striped/raid0 and raid4.
+.IP \(bu 3
+between striped/raid0 and raid5.
+.IP \(bu 3
+between striped/raid0 and raid6.
+.IP \(bu 3
+between raid4 and raid5.
+.IP \(bu 3
+between raid4/raid5 and raid6.
+.IP \(bu 3
+between striped/raid0 and raid10.
+
+.SS Examples
+
+1. Converting an LV from \fBlinear\fP to \fBraid1\fP.
+
+.nf
+# lvs -a -o name,segtype,size vg
+ LV Type LSize
+ lv linear 300.00g
+
+# lvconvert --type raid1 --mirrors 1 vg/lv
+
+# lvs -a -o name,segtype,size vg
+ LV Type LSize
+ lv raid1 300.00g
+ [lv_rimage_0] linear 300.00g
+ [lv_rimage_1] linear 300.00g
+ [lv_rmeta_0] linear 3.00m
+ [lv_rmeta_1] linear 3.00m
+.fi
+
+2. Converting an LV from \fBmirror\fP to \fBraid1\fP.
+
+.nf
+# lvs -a -o name,segtype,size vg
+ LV Type LSize
+ lv mirror 100.00g
+ [lv_mimage_0] linear 100.00g
+ [lv_mimage_1] linear 100.00g
+ [lv_mlog] linear 3.00m
+.IP \(bu 3
between striped and raid4.
.SS Examples
@@ -1052,8 +1105,8 @@ All segments with PE ranges '33-33' provide the out-of-place reshape space.
The dataoffset column shows that the data was moved from initial offset 0 to
2048 sectors on each component DataLV.
-If the RaidLV should be restriped for performance reasons,
-convert the 3-way striped raid6_nr LV to 5-way-striped.
+For performance reasons the raid6_nr RaidLV can be restriped.
+Convert it from 3-way striped to 5-way-striped.
.nf
# lvconvert --stripes 5 -y tb/lv
@@ -1069,18 +1122,18 @@ convert the 3-way striped raid6_nr LV to 5-way-striped.
lv tb rwi-a-r-s- 652.00m 52.94
# lvs -a -o lv_name,attr,segtype,seg_pe_ranges,dataoffset tb
- LV Attr Type PE Ranges DOff
- lv rwi-a-r--- raid6_nr lv_rimage_0:0-33 lv_rimage_1:0-33 lv_rimage_2:0-33 lv_rimage_3:0-33 lv_rimage_4:0-33 lv_rimage_5:0-33 lv_rimage_6:0-33 0
- [lv_rimage_0] iwi-aor--- linear /dev/sda:0-32 0
+ LV Attr Type PE Ranges DOff
+ lv rwi-a-r--- raid6_nr lv_rimage_0:0-33 lv_rimage_1:0-33 lv_rimage_2:0-33 ... lv_rimage_5:0-33 lv_rimage_6:0-33 0
+ [lv_rimage_0] iwi-aor--- linear /dev/sda:0-32 0
[lv_rimage_0] iwi-aor--- linear /dev/sda:34-34
- [lv_rimage_1] iwi-aor--- linear /dev/sdaa:0-32 0
+ [lv_rimage_1] iwi-aor--- linear /dev/sdaa:0-32 0
[lv_rimage_1] iwi-aor--- linear /dev/sdaa:34-34
- [lv_rimage_2] iwi-aor--- linear /dev/sdab:0-32 0
+ [lv_rimage_2] iwi-aor--- linear /dev/sdab:0-32 0
[lv_rimage_2] iwi-aor--- linear /dev/sdab:34-34
- [lv_rimage_3] iwi-aor--- linear /dev/sdac:1-34 0
- [lv_rimage_4] iwi-aor--- linear /dev/sdad:1-34 0
- [lv_rimage_5] iwi-aor--- linear /dev/sdae:1-34 0
- [lv_rimage_6] iwi-aor--- linear /dev/sdaf:1-34 0
+ [lv_rimage_3] iwi-aor--- linear /dev/sdac:1-34 0
+ [lv_rimage_4] iwi-aor--- linear /dev/sdad:1-34 0
+ [lv_rimage_5] iwi-aor--- linear /dev/sdae:1-34 0
+ [lv_rimage_6] iwi-aor--- linear /dev/sdaf:1-34 0
[lv_rmeta_0] ewi-aor--- linear /dev/sda:33-33
[lv_rmeta_1] ewi-aor--- linear /dev/sdaa:33-33
[lv_rmeta_2] ewi-aor--- linear /dev/sdab:33-33
@@ -1090,6 +1143,7 @@ convert the 3-way striped raid6_nr LV to 5-way-striped.
[lv_rmeta_6] ewi-aor--- linear /dev/sdaf:0-0
.fi
+Stripes also can be removed from raid5 and 6.
Convert the 5-way striped raid6_nr LV to 4-way-striped.
The force option needs to be used, because removing stripes
(i.e. image SubLVs) from a RaidLV will shrink its size.
@@ -1105,18 +1159,18 @@ The force option needs to be used, because removing stripes
Logical volume tb/lv successfully converted.
# lvs -a -o lv_name,attr,segtype,seg_pe_ranges,dataoffset tb
- LV Attr Type PE Ranges DOff
- lv rwi-a-r-s- raid6_nr lv_rimage_0:0-33 lv_rimage_1:0-33 lv_rimage_2:0-33 lv_rimage_3:0-33 lv_rimage_4:0-33 lv_rimage_5:0-33 lv_rimage_6:0-33 0
- [lv_rimage_0] Iwi-aor--- linear /dev/sda:0-32 0
+ LV Attr Type PE Ranges DOff
+ lv rwi-a-r-s- raid6_nr lv_rimage_0:0-33 lv_rimage_1:0-33 lv_rimage_2:0-33 ... lv_rimage_5:0-33 lv_rimage_6:0-33 0
+ [lv_rimage_0] Iwi-aor--- linear /dev/sda:0-32 0
[lv_rimage_0] Iwi-aor--- linear /dev/sda:34-34
- [lv_rimage_1] Iwi-aor--- linear /dev/sdaa:0-32 0
+ [lv_rimage_1] Iwi-aor--- linear /dev/sdaa:0-32 0
[lv_rimage_1] Iwi-aor--- linear /dev/sdaa:34-34
- [lv_rimage_2] Iwi-aor--- linear /dev/sdab:0-32 0
+ [lv_rimage_2] Iwi-aor--- linear /dev/sdab:0-32 0
[lv_rimage_2] Iwi-aor--- linear /dev/sdab:34-34
- [lv_rimage_3] Iwi-aor--- linear /dev/sdac:1-34 0
- [lv_rimage_4] Iwi-aor--- linear /dev/sdad:1-34 0
- [lv_rimage_5] Iwi-aor--- linear /dev/sdae:1-34 0
- [lv_rimage_6] Iwi-aor-R- linear /dev/sdaf:1-34 0
+ [lv_rimage_3] Iwi-aor--- linear /dev/sdac:1-34 0
+ [lv_rimage_4] Iwi-aor--- linear /dev/sdad:1-34 0
+ [lv_rimage_5] Iwi-aor--- linear /dev/sdae:1-34 0
+ [lv_rimage_6] Iwi-aor-R- linear /dev/sdaf:1-34 0
[lv_rmeta_0] ewi-aor--- linear /dev/sda:33-33
[lv_rmeta_1] ewi-aor--- linear /dev/sdaa:33-33
[lv_rmeta_2] ewi-aor--- linear /dev/sdab:33-33
@@ -1131,16 +1185,16 @@ The 'R' in the same column of the attribute field shows the freed image Sub LVs
.nf
# lvs -o lv_name,attr,segtype,seg_pe_ranges,dataoffset tb
- LV Attr Type PE Ranges DOff
- lv rwi-a-r-R- raid6_nr lv_rimage_0:0-33 lv_rimage_1:0-33 lv_rimage_2:0-33 lv_rimage_3:0-33 lv_rimage_4:0-33 lv_rimage_5:0-33 lv_rimage_6:0-33 8192
+ LV Attr Type PE Ranges DOff
+ lv rwi-a-r-R- raid6_nr lv_rimage_0:0-33 lv_rimage_1:0-33 lv_rimage_2:0-33 ... lv_rimage_5:0-33 lv_rimage_6:0-33 8192
.fi
Now that the reshape is finished the 'R' atribute on the RaidLV shows images can be removed.
.nf
# lvs -o lv_name,attr,segtype,seg_pe_ranges,dataoffset tb
- LV Attr Type PE Ranges DOff
- lv rwi-a-r-R- raid6_nr lv_rimage_0:0-33 lv_rimage_1:0-33 lv_rimage_2:0-33 lv_rimage_3:0-33 lv_rimage_4:0-33 lv_rimage_5:0-33 lv_rimage_6:0-33 8192
+ LV Attr Type PE Ranges DOff
+ lv rwi-a-r-R- raid6_nr lv_rimage_0:0-33 lv_rimage_1:0-33 lv_rimage_2:0-33 ... lv_rimage_5:0-33 lv_rimage_6:0-33 8192
.fi
This is achieved by repeating the command ("lvconvert --stripes 4 tb/lv" would be sufficient).
@@ -1151,17 +1205,17 @@ This is achieved by repeating the command ("lvconvert --stripes 4 tb/lv" would b
Logical volume tb/lv successfully converted.
# lvs -a -o lv_name,attr,segtype,seg_pe_ranges,dataoffset tb
- LV Attr Type PE Ranges DOff
- lv rwi-a-r--- raid6_nr lv_rimage_0:0-33 lv_rimage_1:0-33 lv_rimage_2:0-33 lv_rimage_3:0-33 lv_rimage_4:0-33 lv_rimage_5:0-33 8192
- [lv_rimage_0] iwi-aor--- linear /dev/sda:0-32 8192
+ LV Attr Type PE Ranges DOff
+ lv rwi-a-r--- raid6_nr lv_rimage_0:0-33 lv_rimage_1:0-33 lv_rimage_2:0-33 ... lv_rimage_5:0-33 8192
+ [lv_rimage_0] iwi-aor--- linear /dev/sda:0-32 8192
[lv_rimage_0] iwi-aor--- linear /dev/sda:34-34
- [lv_rimage_1] iwi-aor--- linear /dev/sdaa:0-32 8192
+ [lv_rimage_1] iwi-aor--- linear /dev/sdaa:0-32 8192
[lv_rimage_1] iwi-aor--- linear /dev/sdaa:34-34
- [lv_rimage_2] iwi-aor--- linear /dev/sdab:0-32 8192
+ [lv_rimage_2] iwi-aor--- linear /dev/sdab:0-32 8192
[lv_rimage_2] iwi-aor--- linear /dev/sdab:34-34
- [lv_rimage_3] iwi-aor--- linear /dev/sdac:1-34 8192
- [lv_rimage_4] iwi-aor--- linear /dev/sdad:1-34 8192
- [lv_rimage_5] iwi-aor--- linear /dev/sdae:1-34 8192
+ [lv_rimage_3] iwi-aor--- linear /dev/sdac:1-34 8192
+ [lv_rimage_4] iwi-aor--- linear /dev/sdad:1-34 8192
+ [lv_rimage_5] iwi-aor--- linear /dev/sdae:1-34 8192
[lv_rmeta_0] ewi-aor--- linear /dev/sda:33-33
[lv_rmeta_1] ewi-aor--- linear /dev/sdaa:33-33
[lv_rmeta_2] ewi-aor--- linear /dev/sdab:33-33
@@ -1254,13 +1308,13 @@ From striped we can convert to raid10
Logical volume tb/lv successfully converted.
# lvs -o lv_name,attr,segtype,seg_pe_ranges,dataoffset tb
- LV Attr Type PE Ranges DOff
- lv rwi-a-r--- raid10 lv_rimage_0:0-32 lv_rimage_4:0-32 lv_rimage_1:0-32 lv_rimage_5:0-32 lv_rimage_2:0-32 lv_rimage_6:0-32 lv_rimage_3:0-32 lv_rimage_7:0-32 0
+ LV Attr Type PE Ranges DOff
+ lv rwi-a-r--- raid10 lv_rimage_0:0-32 lv_rimage_4:0-32 lv_rimage_1:0-32 ... lv_rimage_3:0-32 lv_rimage_7:0-32 0
# lvs -a -o lv_name,attr,segtype,seg_pe_ranges,dataoffset tb
WARNING: Cannot find matching striped segment for tb/lv_rimage_3.
- LV Attr Type PE Ranges DOff
- lv rwi-a-r--- raid10 lv_rimage_0:0-32 lv_rimage_4:0-32 lv_rimage_1:0-32 lv_rimage_5:0-32 lv_rimage_2:0-32 lv_rimage_6:0-32 lv_rimage_3:0-32 lv_rimage_7:0-32 0
+ LV Attr Type PE Ranges DOff
+ lv rwi-a-r--- raid10 lv_rimage_0:0-32 lv_rimage_4:0-32 lv_rimage_1:0-32 ... lv_rimage_3:0-32 lv_rimage_7:0-32 0
[lv_rimage_0] iwi-aor--- linear /dev/sda:2-32 0
[lv_rimage_0] iwi-aor--- linear /dev/sda:34-35
[lv_rimage_1] iwi-aor--- linear /dev/sdaa:2-32 0
@@ -1283,6 +1337,111 @@ From striped we can convert to raid10
.fi
raid10 allows to add stripes but can't remove them.
+
+
+A more ellaborate example to convert from linear to striped
+with interim conversions to raid1 then raid5 followed
+by restripe (4 steps).
+
+We start with the linear LV.
+
+.nf
+# lvs -aoname,attr,size,segtype,syncpercent,datastripes,stripesize,reshapelenle,devices vg
+ LV Attr LSize Type Cpy%Sync #DStr Stripe RSize Devices
+ lv -wi-a----- 128.00m linear 1 0 /dev/sda(0)
+.fi
+
+Then convert it to a 2-way raid1.
+
+.nf
+# lvconvert -m1 vg/lv
+ Logical volume vg/lv successfully converted.
+
+# lvs -aoname,attr,size,segtype,syncpercent,datastripes,stripesize,reshapelenle,devices vg
+ LV Attr LSize Type Cpy%Sync #DStr Stripe RSize Devices
+ lv rwi-a-r--- 128.00m raid1 100.00 2 0 lv_rimage_0(0),lv_rimage_1(0)
+ [lv_rimage_0] iwi-aor--- 128.00m linear 1 0 /dev/sda(0)
+ [lv_rimage_1] iwi-aor--- 128.00m linear 1 0 /dev/sdhx(1)
+ [lv_rmeta_0] ewi-aor--- 4.00m linear 1 0 /dev/sda(32)
+ [lv_rmeta_1] ewi-aor--- 4.00m linear 1 0 /dev/sdhx(0)
+.fi
+
+Once the raid1 LV is fully synchronized we convert it to raid5_n (only 2-way raid1
+LVs can be converted to raid5). We select raid5_n here because it has dedicated parity
+SubLVs at the end and can be converted to striped directly without any additional
+conversion.
+
+.nf
+# lvconvert -y --ty raid5_n vg/lv
+ Using default stripesize 64.00 KiB.
+ Logical volume vg/lv successfully converted.
+
+# lvs -aoname,attr,size,segtype,syncpercent,datastripes,stripesize,reshapelenle,devices vg
+ LV Attr LSize Type Cpy%Sync #DStr Stripe RSize Devices
+ lv rwi-a-r--- 128.00m raid5_n 100.00 1 64.00k 0 lv_rimage_0(0),lv_rimage_1(0)
+ [lv_rimage_0] iwi-aor--- 128.00m linear 1 0 0 /dev/sda(0)
+ [lv_rimage_1] iwi-aor--- 128.00m linear 1 0 0 /dev/sdhx(1)
+ [lv_rmeta_0] ewi-aor--- 4.00m linear 1 0 /dev/sda(32)
+ [lv_rmeta_1] ewi-aor--- 4.00m linear 1 0 /dev/sdhx(0)
+.fi
+
+Now we'll change the number of data stripes from 1 to 5 and request 128K stripe size
+in one command. This will grow the size of the LV by a factor of 5 (we add 4 data stripes
+to the one given). That additonal space can be used by e.g. growing any contained filesystem
+or the LV can be reduced in size after the reshaping conversion has finished.
+
+.nf
+# lvconvert --yes --stripesize 128k --stripes 5 vg/lv
+ Converting stripesize 64.00 KiB of raid5_n LV vg/lv to 128.00 KiB.
+ WARNING: Adding stripes to active logical volume vg/lv will grow it from 32 to 160 extents!
+ Run "lvresize -l32 vg/lv" to shrink it or use the additional capacity.
+ Logical volume vg/lv successfully converted.
+
+# lvs -aoname,attr,size,segtype,syncpercent,datastripes,stripesize,reshapelenle,devices vg
+ LV Attr LSize Type Cpy%Sync #DStr Stripe RSize Devices
+ lv rwi-a-r--- 640.00m raid5_n 100.00 5 128.00k 6 lv_rimage_0(0),lv_rimage_1(0),lv_rimage_2(0),lv_rimage_3(0),lv_rimage_4(0),lv_rimage_5(0)
+ [lv_rimage_0] iwi-aor--- 132.00m linear 1 0 1 /dev/sda(33)
+ [lv_rimage_0] iwi-aor--- 132.00m linear 1 0 /dev/sda(0)
+ [lv_rimage_1] iwi-aor--- 132.00m linear 1 0 1 /dev/sdhx(33)
+ [lv_rimage_1] iwi-aor--- 132.00m linear 1 0 /dev/sdhx(1)
+ [lv_rimage_2] iwi-aor--- 132.00m linear 1 0 1 /dev/sdhw(33)
+ [lv_rimage_2] iwi-aor--- 132.00m linear 1 0 /dev/sdhw(1)
+ [lv_rimage_3] iwi-aor--- 132.00m linear 1 0 1 /dev/sdhv(33)
+ [lv_rimage_3] iwi-aor--- 132.00m linear 1 0 /dev/sdhv(1)
+ [lv_rimage_4] iwi-aor--- 132.00m linear 1 0 1 /dev/sdhu(33)
+ [lv_rimage_4] iwi-aor--- 132.00m linear 1 0 /dev/sdhu(1)
+ [lv_rimage_5] iwi-aor--- 132.00m linear 1 0 1 /dev/sdht(33)
+ [lv_rimage_5] iwi-aor--- 132.00m linear 1 0 /dev/sdht(1)
+ [lv_rmeta_0] ewi-aor--- 4.00m linear 1 0 /dev/sda(32)
+ [lv_rmeta_1] ewi-aor--- 4.00m linear 1 0 /dev/sdhx(0)
+ [lv_rmeta_2] ewi-aor--- 4.00m linear 1 0 /dev/sdhw(0)
+ [lv_rmeta_3] ewi-aor--- 4.00m linear 1 0 /dev/sdhv(0)
+ [lv_rmeta_4] ewi-aor--- 4.00m linear 1 0 /dev/sdhu(0)
+ [lv_rmeta_5] ewi-aor--- 4.00m linear 1 0 /dev/sdht(0)
+.fi
+
+Once the conversion has finished we can can convert to striped.
+
+.nf
+[root at vm46 ~]# lvconvert -y --ty striped vg/lv
+ Logical volume vg/lv successfully converted.
+
+[root at vm46 ~]# lvs -aoname,attr,size,segtype,syncpercent,datastripes,stripesize,reshapelenle,devices vg|sed 's/ *$//'
+ LV Attr LSize Type Cpy%Sync #DStr Stripe RSize Devices
+ lv -wi-a----- 640.00m striped 5 128.00k /dev/sda(33),/dev/sdhx(33),/dev/sdhw(33),/dev/sdhv(33),/dev/sdhu(33)
+ lv -wi-a----- 640.00m striped 5 128.00k /dev/sda(0),/dev/sdhx(1),/dev/sdhw(1),/dev/sdhv(1),/dev/sdhu(1)
+.fi
+
+Reversing these steps wil convert a given striped LV to linear.
+
+Mind the fact that stripes are removed thus the capacity of the RaidLV will shrink.
+
+"lvconvert --stripes 1 vg/lv" for converting to 1 stripe will inform upfront about
+the reduced size to allow for resizing the content or growing the RaidLV before
+actually converting to 1 stripe. The \fB\-\-force\fP option is needed to
+allow stripe removing conversions to prevent data loss.
+
+Of course any interim step can be the intended last one (e.g. striped -> raid1).
..
.SH RAID5 Variants
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