Differences between revisions 1 and 2

LVM

The aim of this page is to summarize the LVM relevant parts.

?TableOfContents

Prerequisites

Installed and running XEN Dom0. (with NAT)

In the test a Debian sid netinstall was used.

Preparations

(1) Test if module is installed:

test:~# modprobe dm-mod
test:~# lsmod|grep dm
dm_snapshot            15552  0
dm_mirror              19152  0
dm_mod                 50232  2 dm_snapshot,dm_mirror

(2) Install Packages

aptitude install lvm2
=>  lvm-common lvm2

(3) Adjust Drive Range

vim /etc/lvm/lvm.conf
 
    # By default we accept every block device
    # filter = [ "a/.*/" ]
    filter = [ "a|/dev/sda4|", "r/.*/" ]

(4) Make sure we have no pre-installed drives

vgscan
  Reading all physical volumes.  This may take a while...
  No volume groups found
vgchange -a y
  No volume groups found

(5) Create a Volume

pvcreate /dev/sda4
  Physical volume "/dev/sda4" successfully created

(6) Create Volume Group

vgcreate vg /dev/sda4
  Volume group "vg" successfully created
(not done: vgextend vg /dev/sdb4)

(7) Create virtual Machine

xen-create-image --hostname buildsid --ip 10.0.2.40 --gateway 10.0.2.40

make LVM snapshot

lvcreate -L 2G --snapshot -n buildsid-disk-ss /dev/vg/buildsid-disk

restore LVM snapshot time

The aim of this section is to measure the time

(1) Start virtual machine

(2) Log into machine

(3) Make some changes

buildsid:~# dd bs=1024 count=100000 if=/dev/urandom of=test.img
100000+0 records in
100000+0 records out
102400000 bytes (102 MB) copied, 25.68 s, 4.0 MB/s

(4) This makes some changes to the snapshot:

  lvdisplay /dev/vg/buildsid-disk-ss
  [...]
  LV Size                10,00 GB
  Current LE             2560
  COW-table size         2,00 GB
  COW-table LE           512
  Allocated to snapshot  4,86%
  Snapshot chunk size    8,00 KB
  [...]

(5) Shut down the machine

(6) An now the test:

time lvremove -f /dev/vg/buildsid-disk-ss; time lvcreate -L 2G --snapshot -n buildsid-disk-ss /dev/vg/buildsid-disk

(7) The result is:

  Logical volume "buildsid-disk-ss" successfully removed

real    0m0.088s
user    0m0.000s
sys     0m0.036s
  Logical volume "buildsid-disk-ss" created

real    0m0.225s
user    0m0.000s
sys     0m0.048s

(8) A second run on an unchanged snapshot:

  Logical volume "buildsid-disk-ss" successfully removed

real    0m0.067s
user    0m0.000s
sys     0m0.032s
  Logical volume "buildsid-disk-ss" created

real    0m0.170s
user    0m0.000s
sys     0m0.052s

Subjective observation: Sometimes it can take up to 3 seconds.

(9) Results:

	remove	create	total time
Debian Sit 10GB/2GB	0.088s	0.225s	0.243s

turnaround time

The trunaround time is the time from t0 (shutting down machine A) to tn (machine B is up). The following stages can be forseen:

Time	Event
t0	trigger shutdown
t1	shutting down machine A
t2	machine is down
t3	start delete snapshot
t4	end delete snapshot
t5	start create snapshot
t6	end create snapshot
t7	start booting machine B
t8	end of booting machine B
t9	sending signal from B

Preparations:

(1) boot the machine

(2) make it is up and running

(3) Copy a ssh key for a user on that

machine to the autorized_key file, so that the user can log in to that machine without password.

The following script measures the time:

time turnaround.pl

The "turnaround.pl" script do work

TODO

-  ⇤ ← Revision 1 as of 2008-05-22 13:55:55 → 
  Size: 278
  Editor: ChristianKuelker
  Comment:  first draft
+   ← Revision 2 as of 2008-05-22 16:15:40 → ⇥
  Size: 3887
  Editor: ChristianKuelker
  Comment: update
-Deletions are marked like this.
+Additions are marked like this.
 Line 1:
-Line 8:
+Line 6:
+[[TableOfContents]]

== Prerequisites ==

Installed and running XEN Dom0. (with NAT)


In the test a Debian sid netinstall was used.
-Line 10:
+Line 17:
- (1) Install lvm-common lvm2
+ (1) Test if module is installed:
-Line 12:
+Line 19:
+{{{
test:~# modprobe dm-mod
test:~# lsmod|grep dm
dm_snapshot            15552  0
dm_mirror              19152  0
dm_mod                 50232  2 dm_snapshot,dm_mirror
}}}

(2) Install Packages
{{{
aptitude install lvm2
=>  lvm-common lvm2
}}}

(3) Adjust Drive Range

{{{
vim /etc/lvm/lvm.conf
-Line 13:
+Line 38:
+    # By default we accept every block device
    # filter = [ "a/.*/" ]
    filter = [ "a|/dev/sda4|", "r/.*/" ]
}}}

(4) Make sure we have no pre-installed drives
{{{
vgscan
  Reading all physical volumes.  This may take a while...
  No volume groups found
vgchange -a y
  No volume groups found
}}}

(5) Create a Volume
{{{
pvcreate /dev/sda4
  Physical volume "/dev/sda4" successfully created
}}}

(6) Create Volume Group
{{{
vgcreate vg /dev/sda4
  Volume group "vg" successfully created
(not done: vgextend vg /dev/sdb4)
}}}

(7) Create virtual Machine
{{{
xen-create-image --hostname buildsid --ip 10.0.2.40 --gateway 10.0.2.40
}}}
-Line 15:
+Line 72:
-{{{lvcreate -L 12M --snapshot -n vol2 /dev/Volg1/vol1}
+{{{
lvcreate -L 2G --snapshot -n buildsid-disk-ss /dev/vg/buildsid-disk
}}}
-Line 17:
+Line 76:
-== restore LVM snapshot ==
+== restore LVM snapshot time ==

The aim of this section is to measure the time

(1) Start virtual machine

(2) Log into machine

(3) Make some changes
{{{
buildsid:~# dd bs=1024 count=100000 if=/dev/urandom of=test.img
100000+0 records in
100000+0 records out
102400000 bytes (102 MB) copied, 25.68 s, 4.0 MB/s
}}} 

(4) This makes some changes to the snapshot:
{{{
  lvdisplay /dev/vg/buildsid-disk-ss
  [...]
  LV Size                10,00 GB
  Current LE             2560
  COW-table size         2,00 GB
  COW-table LE           512
  Allocated to snapshot  4,86%
  Snapshot chunk size    8,00 KB
  [...]
}}}
(5) Shut down the machine

(6)
An now the test:

{{{
time lvremove -f /dev/vg/buildsid-disk-ss; time lvcreate -L 2G --snapshot -n buildsid-disk-ss /dev/vg/buildsid-disk
}}}

(7)
The result is:
{{{
  Logical volume "buildsid-disk-ss" successfully removed

real    0m0.088s
user    0m0.000s
sys     0m0.036s
  Logical volume "buildsid-disk-ss" created

real    0m0.225s
user    0m0.000s
sys     0m0.048s
}}}

(8)
A second run on an unchanged snapshot:
{{{
  Logical volume "buildsid-disk-ss" successfully removed

real    0m0.067s
user    0m0.000s
sys     0m0.032s
  Logical volume "buildsid-disk-ss" created

real    0m0.170s
user    0m0.000s
sys     0m0.052s
}}}

Subjective observation: Sometimes it can take up to 3 seconds.

(9) Results:

||                    || remove || create || total time ||
||Debian Sit 10GB/2GB || 0.088s || 0.225s || 0.243s     ||

== turnaround time ==

The trunaround time is the time from '''t0''' (shutting down machine A) to '''tn''' (machine B is up). The following stages can be forseen:

|| Time  || Event                   ||
|| t0    || trigger shutdown        ||
|| t1    || shutting down machine A ||
|| t2    || machine is down         ||
|| t3    || start delete snapshot   ||
|| t4    || end delete snapshot     ||
|| t5    || start create snapshot   ||
|| t6    || end create snapshot     ||
|| t7    || start booting machine B ||
|| t8    || end of booting machine B||
|| t9    || sending signal from B   ||
-Line 20:
+Line 167:
-== turnaround time ==
+Preparations:

(1) boot the machine

(2) make it is up and running

(3) Copy a ssh key for a user on that 
  machine to the autorized_key file, so that
  the user can log in to that machine without
  password.

The following script measures the time:
{{{
time turnaround.pl
}}}

The "turnaround.pl" script do work

{{{
TODO
}}}

Diff for "CipUX/Feature/Deploy/Lvm"

LVM

Prerequisites

Preparations

make LVM snapshot

restore LVM snapshot time

turnaround time