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man: add more info/examples to lvmraid(7)

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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
This commit is contained in:
Heinz Mauelshagen 2017-03-10 22:40:22 +01:00
parent 15682270f4
commit 164d4a309c
1 changed files with 195 additions and 36 deletions
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man/lvmraid.7.in
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@ -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@vm46 ~]# lvconvert -y --ty striped vg/lv
Logical volume vg/lv successfully converted.
[root@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