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Author help understand disk managment
peter

2005-08-21, 8:45 pm

Could someone point me to a web site with good illustration/explanation on
linux disk concepts including
physical volume, logical volume, volume group, types of linux partition,
extends, ...

I have already visited several linux sites but still don't quite understand
the whole picture. Different sites seem to explain the concepts in a totally
different way.

I came from windows background. If someone could explain the stuff using
windows terminology, or contrast compare with windows, perhaps it would
help.


Lenard

2005-08-21, 8:45 pm

peter wrote:

> Could someone point me to a web site with good
> illustration/explanation on linux disk concepts including
> physical volume, logical volume, volume group, types of linux
> partition, extends, ...
>
> I have already visited several linux sites but still don't quite
> understand the whole picture. Different sites seem to explain the
> concepts in a totally different way.
>
> I came from windows background. If someone could explain the stuff
> using windows terminology, or contrast compare with windows, perhaps
> it would help.



http://www.redhat.com/docs/manuals/...partitions.html
http://www.linuxplanet.com/linuxpla...torials/4269/1/


--
Contained within the Microsoft EULA;
This Limited Warranty is void if failure of the Product has resulted
from accident, abuse, misapplication, abnormal use or a virus.
peter

2005-08-22, 5:52 pm

Thanks, now I know why I was confused. There are two types of file systems
in redhat.

In the simple type, hard drives are partitioned and partitions are mounted.

In the complicated type (LVM), drives are divided into physical volume, then
physical volumes are combineded into a logical volume group, which is like a
big resizable virtual drive. This logical volume group can then be
"partitioned" into logical volumes which can then be mounted and resized at
will.

Is this more or less correct? What is the correct way to refer to the simple
type file system?

"Lenard" <Lenard@127.0.0.1> wrote in message
news:YS9Oe.469$L77.163@newssvr19.news.prodigy.com...
>
>
> http://www.redhat.com/docs/manuals/...partitions.html
> http://www.linuxplanet.com/linuxpla...torials/4269/1/



Anne & Lynn Wheeler

2005-08-22, 5:52 pm

"peter" <nospam@nospam.com> writes:
> Thanks, now I know why I was confused. There are two types of file
> systems in redhat.
>
> In the simple type, hard drives are partitioned and partitions are
> mounted.
>
> In the complicated type (LVM), drives are divided into physical
> volume, then physical volumes are combineded into a logical volume
> group, which is like a big resizable virtual drive. This logical
> volume group can then be "partitioned" into logical volumes which
> can then be mounted and resized at will.
>
> Is this more or less correct? What is the correct way to refer to
> the simple type file system?


disk partitioning, ala ms/dos
... sort of like minidisks from cp/67 ... circa mid-60s

minor ref
http://www.garlic.com/~lynn/2004e.html#38 [REALLY OT!] Overuse of symbolic constants
http://www.garlic.com/~lynn/2004h.html#40 Which Monitor Would You Pick??????
http://www.garlic.com/~lynn/2004k.html#46 Xah Lee's Unixism

LVM started with aix/v3 for rs/6000
included support for things other than straight partitioning,
striping, mirroring, concatenation, etc

as an aside ... journaled file system (JFS) was also done for
for the same rs/6000 aix/v3 release

.....

.... so one flavor is sort of the ms/dos heritage ... modulo minidisks
and virtual machine stuff from the mid-60.

the other flavor is somewhat more unix heritage ... at least from
aix/v3.

--
Anne & Lynn Wheeler | http://www.garlic.com/~lynn/
Lenard

2005-08-22, 5:52 pm

peter wrote:

> Thanks, now I know why I was confused. There are two types of file
> systems in redhat.
>
> In the simple type, hard drives are partitioned and partitions are
> mounted.
>
> In the complicated type (LVM), drives are divided into physical
> volume, then physical volumes are combineded into a logical volume
> group, which is like a big resizable virtual drive. This logical
> volume group can then be "partitioned" into logical volumes which can
> then be mounted and resized at will.
>
> Is this more or less correct? What is the correct way to refer to the
> simple type file system?


First learn how to not top post please.

Second in answer to your questions and comments;
Partitions are partitions and volumes are volumes. You cannot have a
volume without first having one or more partitions. Volumes should not
be considered as big re-sizable virtual drive but as a 'container' for
the partitions.

This should help;

http://linux-ntfs.sourceforge.net/l...ew/volumes.html


--
Contained within the Microsoft EULA;
This Limited Warranty is void if failure of the Product has resulted
from accident, abuse, misapplication, abnormal use or a virus.
peter

2005-08-22, 5:52 pm

"peter" <nospam@nospam.com> wrote in message
news:h%lOe.6391$137.1131@trnddc08...
> Thanks, now I know why I was confused. There are two types of file systems
> in redhat.


Another reason I was confused is caused by the name "logical volume group".
The name implies it is a group of logical volumes when in fact it is a group
of physical volumes. I suggest we rename it "physical volume group".


Anne & Lynn Wheeler

2005-08-22, 5:52 pm

"peter" <nospam@nospam.com> writes:
> Another reason I was confused is caused by the name "logical volume
> group". The name implies it is a group of logical volumes when in
> fact it is a group of physical volumes. I suggest we rename it
> "physical volume group".


one of the reason for the original LVM label ... were options other
than 1:1 mapping between the logical volume and the physical
partition(s) ... aka mirroing, stripping, concatenation.

the ms/pc dos stuff purely did physical partitioning with a 1:1
mapping between the (virtual) disk (for filesystem) and the physical
partition.

when we did ha/cmp product
http://www.garlic.com/~lynn/subtopic.html#hacmp

.... another minor reference
http://www.garlic.com/~lynn/95.html#13

we used lvm mirroring for no-single-point-of-failure ... and JFS for
fast restart after outage.

there were even gimicks played with 3-way mirroring for backup ...
add a (LVM) 3rd mirror on the fly ... wait until it sync'ed ... and
then took one of the mirrored disks offline and sent offsite for
disaster/recovery.

--
Anne & Lynn Wheeler | http://www.garlic.com/~lynn/
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