Software >> OS >> Unix >> Linux >> RHEL >> 7 >> RHCE >> System configuration and management part 3

Configure a system as either an iSCSI target or initiator that persistently mounts an iSCSI target

 
### Setup iSCSI target on rhel7server1

## assume empty disk /dev/sdb available

[root@rhel7server1 ~]# fdisk -l /dev/sdb

Disk /dev/sdb: 10.7 GB, 10737418240 bytes, 20971520 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x7742edc6

   Device Boot      Start         End      Blocks   Id  System



## install targetcli pkg & enable iSCSI target

[root@rhel7server1 ~]# yum install -y targetcli
Loaded plugins: langpacks, product-id, search-disabled-repos, subscription-manager
This system is not registered with an entitlement server. You can use subscription-manager to register.
Package targetcli-2.1.fb46-1.el7.noarch already installed and latest version
Nothing to do

[root@rhel7server1 ~]# systemctl enable target
Created symlink from /etc/systemd/system/multi-user.target.wants/target.service to /usr/lib/systemd/system/target.service.

## configure the target

[root@rhel7server1 ~]# targetcli
Warning: Could not load preferences file /root/.targetcli/prefs.bin.
targetcli shell version 2.1.fb46
Copyright 2011-2013 by Datera, Inc and others.
For help on commands, type 'help'.

/> backstores/block/ create block1 /dev/sdb
Created block storage object block1 using /dev/sdb.

/> ls
o- / ..................................................................................................... [...]
  o- backstores .......................................................................................... [...]
  | o- block .............................................................................. [Storage Objects: 1]
  | | o- block1 .................................................... [/dev/sdb (10.0GiB) write-thru deactivated]
  | |   o- alua ............................................................................... [ALUA Groups: 1]
  | |     o- default_tg_pt_gp ................................................... [ALUA state: Active/optimized]
  | o- fileio ............................................................................. [Storage Objects: 0]
  | o- pscsi .............................................................................. [Storage Objects: 0]
  | o- ramdisk ............................................................................ [Storage Objects: 0]
  o- iscsi ........................................................................................ [Targets: 0]
  o- loopback ..................................................................................... [Targets: 0]

/> iscsi/ create iqn.2020-01.com.myexample:t1
Created target iqn.2020-01.com.myexample:t1.
Created TPG 1.
Global pref auto_add_default_portal=true
Created default portal listening on all IPs (0.0.0.0), port 3260.

/> cd iscsi/iqn.2020-01.com.myexample:t1/tpg1/
/iscsi/iqn.20...ample:t1/tpg1> ls
o- tpg1 ................................................................................. [no-gen-acls, no-auth]
  o- acls ............................................................................................ [ACLs: 0]
  o- luns ............................................................................................ [LUNs: 0]
  o- portals ...................................................................................... [Portals: 1]
    o- 0.0.0.0:3260 ....................................................................................... [OK]

/iscsi/iqn.20...ample:t1/tpg1> luns/ create /backstores/block/block1
Created LUN 0.

/iscsi/iqn.20...ample:t1/tpg1> ls
o- tpg1 ................................................................................. [no-gen-acls, no-auth]
  o- acls ............................................................................................ [ACLs: 0]
  o- luns ............................................................................................ [LUNs: 1]
  | o- lun0 ....................................................... [block/block1 (/dev/sdb) (default_tg_pt_gp)]
  o- portals ...................................................................................... [Portals: 1]
    o- 0.0.0.0:3260 ....................................................................................... [OK]

/iscsi/iqn.20...ample:t1/tpg1> acls/ create iqn.2020-01.com.myexample:client
Created Node ACL for iqn.2020-01.com.myexample:client
Created mapped LUN 0.

/iscsi/iqn.20...ample:t1/tpg1> cd acls/iqn.2020-01.com.myexample:client/

/iscsi/iqn.20...ample:client> set auth userid=lunuser
Parameter userid is now 'lunuser'.

/iscsi/iqn.20...ample:client> set auth password=password
Parameter password is now 'password'.

/iscsi/iqn.20...ample:client> cd ../..

/iscsi/iqn.20...ample:t1/tpg1> ls
o- tpg1 ................................................................................. [no-gen-acls, no-auth]
  o- acls ............................................................................................ [ACLs: 1]
  | o- iqn.2020-01.com.myexample:client ....................................................... [Mapped LUNs: 1]
  |   o- mapped_lun0 .................................................................. [lun0 block/block1 (rw)]
  o- luns ............................................................................................ [LUNs: 1]
  | o- lun0 ....................................................... [block/block1 (/dev/sdb) (default_tg_pt_gp)]
  o- portals ...................................................................................... [Portals: 1]
    o- 0.0.0.0:3260 ....................................................................................... [OK]

/iscsi/iqn.20...ample:t1/tpg1> exit
Global pref auto_save_on_exit=true
Last 10 configs saved in /etc/target/backup.
Configuration saved to /etc/target/saveconfig.json

[root@rhel7server1 ~]# firewall-cmd --permanent --add-port=3260/tcp
success

[root@rhel7server1 ~]# firewall-cmd --reload
success

[root@rhel7server1 ~]# systemctl start target

back to Objectives


### Set up iSCSI Initiator on rhel7client1

[root@rhel7client1 ~]# yum install -y iscsi-initiator-utils
....
  Installing : iscsi-initiator-utils-6.2.0.874-4.el7.x86_64                                                 1/2
  Installing : iscsi-initiator-utils-iscsiuio-6.2.0.874-4.el7.x86_64                                        2/2
  Verifying  : iscsi-initiator-utils-iscsiuio-6.2.0.874-4.el7.x86_64                                        1/2
  Verifying  : iscsi-initiator-utils-6.2.0.874-4.el7.x86_64                                                 2/2

Installed:
  iscsi-initiator-utils.x86_64 0:6.2.0.874-4.el7                                                               

Dependency Installed:
  iscsi-initiator-utils-iscsiuio.x86_64 0:6.2.0.874-4.el7             

[root@rhel7client1 ~]# cd /etc/iscsi

[root@rhel7client1 iscsi]# ls -l
total 20
-rw-r--r--. 1 root root    49 Apr 21  2019 initiatorname.iscsi
-rw-------. 1 root root 12329 Jun 27  2017 iscsid.conf

[root@rhel7client1 iscsi]# vi initiatorname.iscsi

/etc/iscsi/initiatorname.iscsi
InitiatorName=iqn.2020-01.com.myexample:client


[root@rhel7client1 iscsi]# vi iscsid.conf

/etc/iscsi/iscsid.conf
# uncomment and configure these parameters
node.session.auth.authmethod = CHAP
node.session.auth.username = lunuser
node.session.auth.password = password


[root@rhel7client1 iscsi]# systemctl start iscsi

[root@rhel7client1 iscsi]# systemctl enable iscsi

[root@rhel7client1 iscsi]# iscsiadm --mode discovery --type sendtargets --portal rhel7server1
192.168.0.10:3260,1 iqn.2020-01.com.myexample:t1

[root@rhel7client1 iscsi]# iscsiadm --mode node --targetname iqn.2020-01.com.myexample:t1 --portal rhel7server1 --login
Logging in to [iface: default, target: iqn.2020-01.com.myexample:t1, portal: 192.168.0.10,3260] (multiple)
Login to [iface: default, target: iqn.2020-01.com.myexample:t1, portal: 192.168.0.10,3260] successful.


[root@rhel7client1 iscsi]# lsblk --scsi
NAME HCTL       TYPE VENDOR   MODEL             REV TRAN
sda  0:0:0:0    disk VBOX     HARDDISK         1.0  sas
sdb  0:0:1:0    disk VBOX     HARDDISK         1.0  sas
sdc  3:0:0:0    disk LIO-ORG  block1           4.0  iscsi  
sr0  2:0:0:0    rom  VBOX     CD-ROM           1.0  ata

root@rhel7client1 iscsi]# mkfs.ext4  /dev/sdc
mke2fs 1.42.9 (28-Dec-2013)
/dev/sdc is entire device, not just one partition!
Proceed anyway? (y,n) y
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=1024 blocks
655360 inodes, 2621440 blocks
131072 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=2151677952
80 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
    32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632

Allocating group tables: done                           
Writing inode tables: done                           
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done

[root@rhel7client1 iscsi]# blkid /dev/sdc
/dev/sdc: UUID="9da9629b-aded-4bcc-9403-10c909bcf488" TYPE="ext4"


## add the following entry into /etc/fstab

/etc/fstab
# not the additional option _netdev which is for the dependency on
# network being started up first before mounting

UUID=9da9629b-aded-4bcc-9403-10c909bcf488    /mnt/iscsi  ext4    _netdev   0 0


## mkdir the mountpoint directory and then mount

[root@rhel7client1 iscsi]# mkdir /mnt/iscsi

[root@rhel7client1 iscsi]# mount -a

[root@rhel7client1 iscsi]# df -h  | grep iscsi
Filesystem             Size  Used Avail Use% Mounted on
/dev/sdc               9.8G   37M  9.2G   1% /mnt/iscsi

## check the iscsi session

[root@rhel7client1 iscsi]# iscsiadm -m session -P 3
iSCSI Transport Class version 2.0-870
version 6.2.0.874-2
Target: iqn.2020-01.com.myexample.rhel7server1:t1 (non-flash)
    Current Portal: 192.168.0.10:3260,1
    Persistent Portal: 192.168.0.10:3260,1
        **********
        Interface:
        **********
        Iface Name: default
        Iface Transport: tcp
        Iface Initiatorname: iqn.2020-01.com.myexample:client
        Iface IPaddress: 192.168.0.20
        Iface HWaddress: <empty>
        Iface Netdev: <empty>
        SID: 1
        iSCSI Connection State: LOGGED IN
        iSCSI Session State: LOGGED_IN
        Internal iscsid Session State: NO CHANGE
        *********
        Timeouts:
        *********
        Recovery Timeout: 120
        Target Reset Timeout: 30
        LUN Reset Timeout: 30
        Abort Timeout: 15
        *****
        CHAP:
        *****
        username: lunuser
        password: ********
        username_in: <empty>
        password_in: ********
        ************************
        Negotiated iSCSI params:
        ************************
        HeaderDigest: None
        DataDigest: None
        MaxRecvDataSegmentLength: 262144
        MaxXmitDataSegmentLength: 262144
        FirstBurstLength: 65536
        MaxBurstLength: 262144
        ImmediateData: Yes
        InitialR2T: Yes
        MaxOutstandingR2T: 1
        ************************
        Attached SCSI devices:
        ************************
        Host Number: 3    State: running
        scsi3 Channel 00 Id 0 Lun: 0
            Attached scsi disk sdc        State: running

## when about to reboot, it is recommended to umount the iscsi mountpoint and stop iscsi initiator service

## after reboot, the service will be autostarted and the mountpoint automounted


back to Objectives

 

Produce and deliver reports on system utilization (processor, memory, disk, and network)

 

 
### Produce Reports on System Utilization

## REAL TIME monitoring of System Utilization - use dstat

# install dstat

[root@rhel7server1 ~]# yum install -y dstat

# run to show utilization in real time

[root@rhel7server1 ~]# dstat
You did not select any stats, using -cdngy by default.
----total-cpu-usage---- -dsk/total- -net/total- ---paging-- ---system--
usr sys idl wai hiq siq| read  writ| recv  send|  in   out | int   csw
  7   1  92   1   0   0|  82k   13k|   0     0 |   0     0 | 205   205
 25   1  74   0   0   0|   0     0 |   0     0 |   0     0 | 428   277
 18   1  81   0   0   0|   0     0 | 139B    0 |   0     0 | 380   276
 24   0  76   0   0   0|   0     0 | 232B    0 |   0     0 | 378   212
...
<Ctrl-C to abort>

# display CPU utilization (only) in real time

[root@rhel7server1 ~]# dstat -c
----total-cpu-usage----
usr sys idl wai hiq siq
  7   1  92   1   0   0
 28   1  71   0   0   0
 28   1  71   0   0   0

# display Memory utilization (only) in realtime

[root@rhel7server1 ~]# dstat -m
------memory-usage-----
 used  buff  cach  free
 899M 2224k  610M 2280M
 899M 2224k  610M 2280M
 899M 2224k  610M 2280M^

# display Disk io utilization (only) in real time
[root@rhel7server1 ~]# dstat -d
-dsk/total-
 read  writ
  80k   13k
   0     0
   0     0
   0     0

# display paging (only) in real time

[root@rhel7server1 ~]# dstat -g
---paging--
  in   out
   0     0
   0     0
   0     0

# display multiple utilization parameters in real time

[root@rhel7server1 ~]# dstat -tcm
----system---- ----total-cpu-usage---- ------memory-usage-----
     time     |usr sys idl wai hiq siq| used  buff  cach  free
13-03 10:17:58|  7   1  92   1   0   0| 901M 2224k  612M 2276M
13-03 10:17:59| 24   1  75   0   0   0| 901M 2224k  612M 2276M
13-03 10:18:00| 12   1  87   0   0   0| 901M 2224k  612M 2276M
13-03 10:18:01| 25   1  74   0   0   0| 901M 2224k  612M 2276M

## COLLECTING HISTORICAL System Utilization - use sysstat service

## install sysstat

# Note:
# 1. collects sar data in /var/log/sa
# 2. configured cron jobs in /etc/crond.d/
# 3. sadf is the command to view sar files

[root@rhel7server1 ~]# yum install -y sysstat

# enable and start the sysstat service

root@rhel7server1 ~]# systemctl enable sysstat
Created symlink from /etc/systemd/system/multi-user.target.wants/sysstat.service to /usr/lib/systemd/system/sysstat.service.

[root@rhel7server1 ~]# systemctl start sysstat

[root@rhel7server1 ~]# systemctl status sysstat
‚óŹ sysstat.service - Resets System Activity Logs
   Loaded: loaded (/usr/lib/systemd/system/sysstat.service; enabled; vendor preset: enabled)
   Active: active (exited) since Fri 2020-03-13 10:30:37 EDT; 7s ago
  Process: 7254 ExecStart=/usr/lib64/sa/sa1 --boot (code=exited, status=0/SUCCESS)
 Main PID: 7254 (code=exited, status=0/SUCCESS)

Mar 13 10:30:37 rhel7server1 systemd[1]: Starting Resets System Activity Logs...
Mar 13 10:30:37 rhel7server1 systemd[1]: Started Resets System Activity Logs.


# note that sadf is part of this sysstat package

[root@rhel7server1 ~]# rpm -qf /usr/bin/sadf
sysstat-10.1.5-12.el7.x86_64

# eg display the SAR data between 09:00 and 09:40 on the 10th of the month
# -s : start time
# -e : end time
# -T : displaying local timestamp (instead of UTC)

root@rhel7server1 ~]# sadf -s 08:00:00 -e 10:00:00 -T /var/log/sa/sa10
rhel7server1    -1    2020-03-10 09:12:37    LINUX-RESTART
rhel7server1    598    2020-03-10 09:30:01    all    %user    0.21
rhel7server1    598    2020-03-10 09:30:01    all    %nice    0.00
rhel7server1    598    2020-03-10 09:30:01    all    %system    0.34
rhel7server1    598    2020-03-10 09:30:01    all    %iowait    0.04
rhel7server1    598    2020-03-10 09:30:01    all    %steal    0.00
rhel7server1    598    2020-03-10 09:30:01    all    %idle    99.41
rhel7server1    599    2020-03-10 09:40:01    all    %user    0.10
rhel7server1    599    2020-03-10 09:40:01    all    %nice    0.00
rhel7server1    599    2020-03-10 09:40:01    all    %system    0.21
rhel7server1    599    2020-03-10 09:40:01    all    %iowait    0.00
rhel7server1    599    2020-03-10 09:40:01    all    %steal    0.00
rhel7server1    599    2020-03-10 09:40:01    all    %idle    99.69
rhel7server1    598    2020-03-10 09:50:01    all    %user    0.10
rhel7server1    598    2020-03-10 09:50:01    all    %nice    0.00
rhel7server1    598    2020-03-10 09:50:01    all    %system    0.21
rhel7server1    598    2020-03-10 09:50:01    all    %iowait    0.00
rhel7server1    598    2020-03-10 09:50:01    all    %steal    0.00
rhel7server1    598    2020-03-10 09:50:01    all    %idle    99.69

# e.g. the same data in semicolon delimited output (-d)

root@rhel7server1 ~]# sadf -s 08:00:00 -e 10:00:00 -T -d /var/log/sa/sa10
rhel7server1;-1;2020-03-10 09:12:37;LINUX-RESTART
# hostname;interval;timestamp;CPU;%user;%nice;%system;%iowait;%steal;%idle
rhel7server1;598;2020-03-10 09:30:01;-1;0.21;0.00;0.34;0.04;0.00;99.41
rhel7server1;599;2020-03-10 09:40:01;-1;0.10;0.00;0.21;0.00;0.00;99.69
rhel7server1;598;2020-03-10 09:50:01;-1;0.10;0.00;0.21;0.00;0.00;99.69

## adding sar options to the same report
## the parameters following -- are the sar options

[root@rhel7server1 ~]# sadf -s 08:00:00 -e 10:00:00 -T /var/log/sa/sa10 -- -r -dp -n DEV | head -10
rhel7server1    -1    2020-03-10 09:12:37    LINUX-RESTART
rhel7server1    598    2020-03-10 09:30:01    -    kbmemfree    3168588
rhel7server1    598    2020-03-10 09:30:01    -    kbmemused    713292
rhel7server1    598    2020-03-10 09:30:01    -    %memused    18.37
rhel7server1    598    2020-03-10 09:30:01    -    kbbuffers    2224
rhel7server1    598    2020-03-10 09:30:01    -    kbcached    329120
rhel7server1    598    2020-03-10 09:30:01    -    kbcommit    1305152
rhel7server1    598    2020-03-10 09:30:01    -    %commit    16.43
rhel7server1    598    2020-03-10 09:30:01    -    kbactive    309736
rhel7server1    598    2020-03-10 09:30:01    -    kbinact    251060

## SYNTAX

sadf  [ -C ] [ -d | -j | -p | -x ] [ -H ] [ -h ] [ -T | -t | -U ] [ -V ] [ -P { cpu [,...] | ALL } ] [
       -s [ hh:mm:ss ] ] [ -e [ hh:mm:ss ] ] [ -- sar_options ] [ interval [ count ] ] [ datafile ]

 back to Objectives


 

Use shell scripting to automate system maintenance tasks

 

Example - ASCII greater/less than comparison

veg1=carrots
veg2=tomatoes

if [[ "$veg1" < "$veg2" ]]
then
  echo "Although $veg1 precede $veg2 in the dictionary,"
  echo -n "this does not necessarily imply anything "
  echo "about my culinary preferences."
else
  echo "What kind of dictionary are you using, anyhow?"
fi


Exammple - NOT

if [ ! -f $FILENAME ]
then
  ...


Example - OR

if [ $condition1 ] || [ $condition2 ]
# Same as:  if [ $condition1 -o $condition2 ]
# Returns true if either condition1 or condition2 holds true...

if [[ $condition1 || $condition2 ]]    # Also works.
#  Note that || operator not permitted inside brackets
#+ of a [ ... ] construct.


Example - AND

if [ $condition1 ] && [ $condition2 ]
#  Same as:  if [ $condition1 -a $condition2 ]
#  Returns true if both condition1 and condition2 hold true...

if [[ $condition1 && $condition2 ]]    # Also works.
#  Note that && operator not permitted inside brackets
#+ of [ ... ] construct.


Example - variable assignment

a=28
echo $a   # 28


Example - arithmetic

## using let
let z=5+3 # no spaces, double quotes optional
# OR
let "z = 5 + 3"   # enclose in double quote if spaces used
echo $z     # 8

## using backtick
z=`expr 5 + 3`    # space separator is mandatory
echo $z

## using double parentheses
z=$((5+3))
echo $z


Example - $ variables

$! pid of the last job run in the background
$? is the exit status of the last command
$_ final argumant of previous command
$$ pid of the script itself
$n - positional parameter n e.g. replacebegin:content:replaceend
$# - total number of command line arguments
$* - all of the positional parameters as a single word
$@ - all of the positional paramters


Example - LOOPS - while

while [ condition ]
do
 command(s)...
done


Example - Reading and parsing files

cat $filename |   # Supply input from a file.
while read line   # As long as there is another line to read ...
do
  ...
done

OR

while read line
do
  ...
done < $filename


Example - LOOPS - until

#!/bin/bash

END_CONDITION=end

until [ "$var1" = "$END_CONDITION" ]
# Tests condition here, at top of loop.
do
  echo "Input variable #1 "
  echo "($END_CONDITION to exit)"
  read var1
  echo "variable #1 = $var1"
  echo
done  


Example - Branching - Case

#!/bin/bash

echo; echo "Hit a key, then hit return."
read Keypress

case "$Keypress" in
  [[:lower:]]   )
                  echo "Lowercase letter"
                  ;;
  [[:upper:]]   )
                  echo "Uppercase letter"
                  ;;
  [0-9]         )
                  echo "Digit"
                  ;;
  *             )
                  echo "Punctuation, whitespace, or other"
                  ;;
esac      
#  ranges of characters in [square brackets],
#  POSIX ranges in [[double square brackets]].


Example - Select menu

select choice in one two three
do
 you entered $choice
 break
done

## Select the numeric buttet point number besides the option and not the option value itself


Example - Here document

COMMAND <<InputComesFromHERE
...
...
...
InputComesFromHERE