Docker : Difference between save and export

http://tuhrig.de/difference-between-save-and-export-in-docker/

So what’s the difference between both? Well, as we saw the exported version is slightly smaller. That is because it is flattened, which means it lost its history and meta-data.

As you can see there, the exported-imported image has lost all of its history whereas the saved-loaded image still have its history and layers. This means that you cannot do any rollback to a previous layer if you export-import it while you can still do this if you save-load the whole (complete) image (you can go back to a previous layer by using docker tag <LAYER ID> <IMAGE NAME>).

install R

yum install libXmu libicu libtcl tcl tk texlive-dvips texlive-latex
rpm -ivh R-core-3.1.3-1.el6.x86_64.rpm
rpm -ivh rstudio-0.98.1103-x86_64.rpm

Asymmetric Logical Unit Access (ALUA)

https://kb.netapp.com/support/index?page=content&id=3012899

What is Asymmetric Logical Unit Access?
Asymmetric Logical Unit Access (ALUA), also known as Target Port Groups Support (TPGS), is a set of SCSI concepts and commands that define path prioritization for SCSI devices. ALUA is a formalized way to describe SCSI port status, and access characteristics. In short, it describes paths as fast, slow, or down and the transitions between these states in a standards-compliant manner. This standard is designed to define the protocol on how multipath IO should be managed between hosts and storage devices. It will also reduce vendor-specific coding and complexity.

Linux : Install docker-io

Red Hat 6.6

Download the following rpm from http://dl.fedoraproject.org/pub/epel/6/x86_64/repoview/

docker-io-1.4.1-3.el6.x86_64.rpm
lua-lxc-1.0.7-1.el6.x86_64.rpm
lua-alt-getopt-0.7.0-1.el6.noarch.rpm
lxc-1.0.7-1.el6.x86_64.rpm
lua-filesystem-1.4.2-1.el6.x86_64.rpm
lxc-libs-1.0.7-1.el6.x86_64.rpm


# rpm -Uvh *.rpm
warning: docker-io-1.4.1-3.el6.x86_64.rpm: Header V3 RSA/SHA256 Signature, key ID 0608b895: NOKEY
Preparing...                ########################################### [100%]
   1:lxc-libs               ########################################### [ 17%]
   2:lua-filesystem         ########################################### [ 33%]
   3:lua-lxc                ########################################### [ 50%]
   4:lua-alt-getopt         ########################################### [ 67%]
   5:lxc                    ########################################### [ 83%]
   6:docker-io              ########################################### [100%]

# chkconfig --list docker
docker          0:off   1:off   2:on    3:on    4:on    5:on    6:off

# service docker start
Starting cgconfig service:                                 [  OK  ]
Starting docker:                                           [  OK  ]

https://access.redhat.com/articles/881893
http://developerblog.redhat.com/2014/05/15/practical-introduction-to-docker-containers/

Docker has an official CentOS 6 repository which they support:

• https://index.docker.io/_/centos/

Download the docker image zip file manually

# cat centos-7-20150304_1234-docker.tar.xz | docker import - centos7:base
f4f6169a4b1175b2ed2f9c9f95369f8eec04b28c41b946280f45205e58bc7c05
# docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             VIRTUAL SIZE
centos7             base                f4f6169a4b11        14 seconds ago      210 MB


Create docker image from my own system 

1. Create the tar files for your file system, simply could be
   

   tar --numeric-owner --exclude=/proc --exclude=/sys -cvf centos6-base.tar /
   

2. Transfer the tar file to other docker system if not installed locally and import it
   

   cat centos6-base.tar | docker import - centos6-base
   

3. Now you can verify by running it.
   

   docker run -i -t centos6-base cat /etc/redhat-release 

   tar --numeric-owner --exclude=/proc --exclude=/sys --exclude=/root \

   --exclude=/var --exclude=/home --exclude=/docker --exclude=/tmp \

   -cvf centos6-base.tar /

   cat centos6-base.tar | docker import - centos6-base
   500e53a55f35cb64724a544b6b94d2db9629f9910564a3611ab106b78b7fd62f
    

   docker images
   REPOSITORY          TAG                 IMAGE ID            CREATED             VIRTUAL SIZE
   centos6-base        latest              500e53a55f35        53 seconds ago      2.621 GB
    

Linux : Introduction to Linux Containers

https://access.redhat.com/articles/1353593

Python script for multipath configuration creation

import os
A = []
B = []
C = 0
LUNPATH = set()
M_LUNPATH = set()
HOST_DEVICE = set()
HOST_DEVICE_LIST = []
HOST_STRING = "Host Device:"
HOST_LUN = {}
p = os.popen('sanlun lun show all', "r")
while 1:
        line = p.readline()
        if not line: break
        #print line
        A = line.split()
        #print len(A)
        if len(A) > 2 :
                controller = A[0]
                lunpathname = A[1]
                print lunpathname, controller
                if lunpathname == "device": continue
                if lunpathname == "lun-pathname": continue
                LUNPATH.add(lunpathname)

                p2 = os.popen('sanlun lun show -p '+controller+":"+lunpathname, "r")
                while 1:
                        line2 = p2.readline()
                        if not line2: break
                        if line2.find(HOST_STRING) != -1 :
                                print line2
                                B = line2.split()
                                print len(B)
                                C = len(B)-1
                                print B[C]
                                HOST_DEVICE.add(B[C])
                                #HOST_DEVICE_LIST.append(B[C])
                                HOST_LUN.update( {B[C]:lunpathname} )



print LUNPATH
for i in LUNPATH:
        # print i
        i = i.replace("/vol/","") # get rid of /vol/
        i = i.replace("/","_") # replace / with _
        M_LUNPATH.add(i)

for i in M_LUNPATH:
        print i

#HOST_DEVICE_LIST.sort()

#for i in HOST_DEVICE_LIST:
#       print i
#       HOST_DEVICE.add(i)

for i in HOST_DEVICE:
        print i

print HOST_LUN

print "mpathconf --enable --with_multipathd y"
print "multipaths {"
for i in HOST_DEVICE:
        #print i
        #print HOST_LUN.get(i)
        j = HOST_LUN.get(i)
        j = j.replace("/vol/","") # get rid of /vol/
        j = j.replace("/","_") # replace / with _
        print "         multipath {"
        print "                 wwid    " + i
        print "                 alias   " + j
        print "         }"

print "}"

print "service multipathd reload"

Linux : dmidecoe command

In a physical server :
# dmidecode -s system-manufacturer
Hewlett-Packard

In a VM :
# dmidecode -s system-manufacturer
VMware, Inc.

When calling HP support, to provide serial number :
dmidecode -s chassis-serial-number