What is mirror and sub mirror in RAID -1 SVM

UNIX Solaris
1

Hi ,

I am new to SVM .when i try to learn RAID 1 , first they are creating two RAID 0 strips through

metainit d51 1 1 c0t0d0s2

metainit d52 1 1 c1t0d0s2

In the next step

metainit d50 -m d51
d50: Mirror is setup

next step is

metaattach d50 d52
d50 : submirror d52 is attached

Please guide me what is the mirror and sub mirror. i knew the RAID 1 concept but i like to know the difference between mirror and the sub mirror and one way mirroring , two way mirroring.

Thanks
MaroV

2

in your example d50 is the mirror, d51 and d52 are the sub mirrors.

d51 and d52 are meta-devices that reference the real slice on the disk. d50 is the meta-device that references both sub-mirrors, d51 and d52. Read/write actions go to d50, SVM then applies the read/write to both sub-mirrors at the same time thus maintaining the RAID1.

3

You should not mirror slice 2.

4

Can any one can guide me what is sub mirror and how its differ from mirror in RAID (SVM):confused:

Thanks
MaroV

5

the mirror (top device) contains sub devices. thats all...

for example:

d0--d10
 |
 ---d20

d0 = top device = mirror
d10/d20 = sub devices = sub mirror

6

Some more explanation from the above diagram:

d0 - a meta device (logical device), this is the actual mirror we use to store the data.

d10 & d20 - these are the sub-mirrors formed by two different slices.

The writting is done in d0 but physically, d0 writes the data into two sub-mirrors (d10 & d20 ). When we perform any kind of operation with this raid device, we only point d0.
Means, d0 is the actual raid device we refer.

                                   -  d10
                                 \-

Writting to ---------- d0 -
-
- d20

Please write if this is still unclear to you.

Thanks,
Deepak Tiwari

7

For your reading and understanding
:- Solaris Volume Manager Administration Guide - Sun Microsystems

8

Hi friends,

Thanks a lot for helping me to know the difference .

Thanks
MaroV