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Creare 4 volumi con LVM e farne un RAID 1+0

STATO DISHI
Ho 4 dischi da 1 GB l’uno gia` formattati con mkfs.ext3 e sono: /dev/sdb1, /dev/sdc1, /dev/sdd1, /dev/sde1.
[root@server backup]# for i in sdb sdc sdd sde; do fdisk -l /dev/$i | grep 83 | awk ‘{print $1,$4}’; done
/dev/sdb1 1044193+
/dev/sdc1 1044193+
/dev/sdd1 1044193+
/dev/sde1 1044193+

PHYSICAL VOLUMES
Creo i Physical volumes da utilizzare:
pvcreate
pvcreate /dev/sdc1
pvcreate /dev/sdd1
pvcreate /dev/sde1

[root@server ~]# pvscan
PV /dev/sdb1 VG vg_raid lvm2 [1016.00 MB / 0 free]
PV /dev/sdc1 VG vg_raid lvm2 [1016.00 MB / 0 free]
PV /dev/sdd1 VG vg_raid lvm2 [1016.00 MB / 0 free]
PV /dev/sde1 VG vg_raid lvm2 [1016.00 MB / 0 free]

[root@server ~]# pvdisplay
— Physical volume —
PV Name /dev/sdb1
VG Name vg_raid
PV Size 1019.72 MB / not usable 3.72 MB
Allocatable yes (but full)
PE Size (KByte) 4096
Total PE 254
Free PE 0
Allocated PE 254
PV UUID gKZnyM-H3m1-kvoj-Tu0g-nL5v-OTkN-3fM0FM
—
— Physical volume —
PV Name /dev/sdc1
VG Name vg_raid
PV Size 1019.72 MB / not usable 3.72 MB
Allocatable yes (but full)
PE Size (KByte) 4096
Total PE 254
Free PE 0
Allocated PE 254
PV UUID GgrkBe-lqZt-drvh-P2jP-NXVq-rE5t-Whs4Vu
—
— Physical volume —
PV Name /dev/sdd1
VG Name vg_raid
PV Size 1019.72 MB / not usable 3.72 MB
Allocatable yes (but full)
PE Size (KByte) 4096
Total PE 254
Free PE 0
Allocated PE 254
PV UUID Fr6LqF-1uxe-QwDB-IDyi-qVtC-OWxV-jHWWSh
—
— Physical volume —
PV Name /dev/sde1
VG Name vg_raid
PV Size 1019.72 MB / not usable 3.72 MB
Allocatable yes (but full)
PE Size (KByte) 4096
Total PE 254
Free PE 0
Allocated PE 254
PV UUID Q1FINZ-cTak-IQHE-ob8o-Rb4w-FyrU-MZ74N1

VOLUME GROUPS
Creo il volume group vg_raid e lo assegno a tutti e quattro i physical volumes con:
vgcreate vg_raid /dev/sdb1 /dev/sdc1 /dev/sdd1 /dev/sde1

[root@server ~]# vgscan
Reading all physical volumes. This may take a while…
Found volume group “vg_raid” using metadata type lvm2

[root@server ~]# vgdisplay
— Volume group —
VG Name vg_raid
System ID
Format lvm2
Metadata Areas 4
Metadata Sequence No 13
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 4
Open LV 4
Max PV 0
Cur PV 4
Act PV 4
VG Size 3.97 GB
PE Size 4.00 MB
Total PE 1016
Alloc PE / Size 1016 / 3.97 GB
Free PE / Size 0 / 0
VG UUID aBr3nQ-ITfN-uw6f-wbNy-72XP-hzIH-hyc1vg

LOGICAL VOLUMES
Creo i volume group chimandoli lv_disc[1-4] utilizzando il valore di phycal extentes di default (4Mb) e impostando la dimensione corretta in modo da utilizzare tutto il disco a disposizione:
lvcreate -L 1016M -v -n lv_disc1 vg_raid
lvcreate -L 1016M -v -n lv_disc2 vg_raid
lvcreate -L 1016M -v -n lv_disc3 vg_raid
lvcreate -L 1016M -v -n lv_disc4 vg_raid

[root@server ~]# lvscan
ACTIVE ‘/dev/vg_raid/lv_disc1′ [1016.00 MB] inherit
ACTIVE ‘/dev/vg_raid/lv_disc2′ [1016.00 MB] inherit
ACTIVE ‘/dev/vg_raid/lv_disc3′ [1016.00 MB] inherit
ACTIVE ‘/dev/vg_raid/lv_disc4′ [1016.00 MB] inherit

[root@server backup]# lvdisplay
— Logical volume —
LV Name /dev/vg_raid/lv_disc1
VG Name vg_raid
LV UUID 8D4g0I-71Wi-l5G0-w1NU-K8Ow-C6o2-PmOrdq
LV Write Access read/write
LV Status available
# open 1
LV Size 1016.00 MB
Current LE 254
Segments 1
Allocation inherit
Read ahead sectors 0
Block device 253:5
—
— Logical volume —
LV Name /dev/vg_raid/lv_disc2
VG Name vg_raid
LV UUID gT5Opa-atHu-0XZT-ezPp-dWMt-3UJW-8N6pmY
LV Write Access read/write
LV Status available
# open 1
LV Size 1016.00 MB
Current LE 254
Segments 1
Allocation inherit
Read ahead sectors 0
Block device 253:6
—
— Logical volume —
LV Name /dev/vg_raid/lv_disc3
VG Name vg_raid
LV UUID 0sajhH-mKSV-4PIC-s0dq-mJIi-wpMd-WNZOZg
LV Write Access read/write
LV Status available
# open 1
LV Size 1016.00 MB
Current LE 254
Segments 1
Allocation inherit
Read ahead sectors 0
Block device 253:7
—
— Logical volume —
LV Name /dev/vg_raid/lv_disc4
VG Name vg_raid
LV UUID BYpwZA-H9hQ-cq7i-iNBl-sGgs-Zn6b-52M3fQ
LV Write Access read/write
LV Status available
# open 1
LV Size 1016.00 MB
Current LE 254
Segments 1
Allocation inherit
Read ahead sectors 0
Block device 253:8

CREO IL RAID10
Il raid 10 o raid 1+0 non e` altro che uno stripe di 2 mirror e si crea in questo modo:
mdadm --create /dev/md0 --level=raid10 --raid-devices=4 /dev/vg_raid/lv_disc1 /dev/vg_raid/lv_disc2 /dev/vg_raid/lv_disc3 /dev/vg_raid/lv_disc4

mkfs.ext3 /dev/md0
mkdir /mnt/prova
mount -t ext3 /dev/md0 /mnt/prova

CONTROLLARE LO STATO DEL RAID
Con mdadm –detail si puo` vedere lo stato del Raid e altre informazioni utili:
[root@server ~]# mdadm –detail /dev/md0
/dev/md0:
Version : 00.90.03
Creation Time : Tue Apr 1 22:07:34 2008
Raid Level : raid10
Array Size : 2080640 (2032.22 MiB 2130.58 MB)
Device Size : 1040320 (1016.11 MiB 1065.29 MB)
Raid Devices : 4
Total Devices : 4
Preferred Minor : 0
Persistence : Superblock is persistent
-
Update Time : Tue Apr 1 22:28:23 2008
State : clean
Active Devices : 4
Working Devices : 4
Failed Devices : 0
Spare Devices : 0
-
Layout : near=2, far=1
Chunk Size : 64K
-
UUID : 4b9568cf:2ae49f9e:447c6720:149c5f6d
Events : 0.2
-
Number Major Minor RaidDevice State
0 253 5 0 active sync /dev/vg_raid/lv_disc1
1 253 6 1 active sync /dev/vg_raid/lv_disc2
2 253 7 2 active sync /dev/vg_raid/lv_disc3
3 253 8 3 active sync /dev/vg_raid/lv_disc4