gnu linux disk

Table of Contents:

• disk
  • scsi
    • lsscsi
      • ubuntu
      • centos
    • list scsi devices
    • list scsi hosts
    • rescan scsi
    • remove disk from sci
  • fdisk
    • list
    • format and partition
  • mount new disk using the mount command
  • LVM
    • install on ubuntu
    • install on centos
    • enable
    • pv ( LVMs physical volume )
      • create
      • list , display
    • vg (volume group)
      • create vg
      • list VGs or get vg details
    • lv ( logical volume )
      • create lv in existing vg
      • Display

disk

scsi

lsscsi

ubuntu

cat /proc/scsi/scsi

centos

yum install lsscsi

list scsi devices

cat /proc/scsi/scsi

list scsi hosts

ls /sys/class/scsi_host

rescan scsi

echo "- - -" > /sys/class/scsi_host/host#/scan
fdisk -l
tail -f /var/log/message

remove disk from sci

echo 1 > /sys/block/sdc/device/delete

fdisk

list

fdisk -l

format and partition

fdisk /dev/sdx

options :

• n – create a new partition
• p – print the partition table

• can specify size , start and endpoint

• d – delete a partition
• w – write the new partition table and exit
• q – quit without saving changes

mount new disk using the mount command

mkdir /disk1
mount /dev/sdx /disk1
df -H

• mount automaticaly on reboot ( add to /etc/fstab)

/dev/sdx               /disk1           ext3    defaults        1 2

LVM

install on ubuntu

apt install lvm2

install on centos

yum install lvm2*

enable

systemctl enable lvm2-lvmetad.service
systemctl enable lvm2-lvmetad.socket
systemctl start lvm2-lvmetad.service
systemctl start lvm2-lvmetad.socket

pv ( LVMs physical volume )

create

pvcreate used to prepare a disk partition or a whole disk for use by LVM

pvcreate /dev/sd

list , display

To get LVM's internal view and details, use LVM commands Lists : use the lvs and pvs commands with option --segments Detailed view: use the lvdisplay and pvdisplay commands with option -m 1- lvs

• List the physical segments used by a logical volume :

lvs --segments /dev/vg_ssd/lv_videos -o +lv_size,devices

• List the physical extents of a given LV. Useful to move those segments (using pvmove):

lvs  /dev/vg_ssd/lv_videos -o seg_pe_ranges

3- lvdisplay

• List the physical segments of a given logical volume, among other information:

lvdisplay -m /dev/vg_ssd/lv_videos

4- pvdisplay

• Display the Logical volume associated with a given physical volume , among other information:

pvdisplay -m /dev/sdb1

5- pvs

• list the logical volume (segments) inside a given Physical Volume:

pvs  /dev/sdb1  --segments  -o +lv_name,lv_size

• Complex command, but full list :

 pvs   --segments  -o pv_name,pv_size,seg_size,vg_name,lv_name,lv_size,seg_pe_ranges

vg (volume group)

At least one physical volume is required to create a volume group.

create vg

vgcreate

 vgcreate testvg /dev/sdx1 /dev/sdx2 ...

list VGs or get vg details

vgdisplay testvg #testvg is optional

lv ( logical volume )

create lv in existing vg

lvcreate -n lv_data1 --size 12G testvg

• options: -n : volume name --size[-L] : volume lv size -p{r|rw} : permision -M{y|n} : persistent

Display

lvdisplay