I am working for a community where several people are engaged for 4 different development projects. we are planning to have a samba server to store our data.

Now the problem is that I have created a share in which @groupa, @groupb and @groupc are allowed to read and write. But three of the members of @groupb are only allowed to for read permission only.

The share that I have created is as follows

[jonodev]
path = /mnt/jonodev
comment =
writeable = yes
browseable = yes
create mode = 755
directory mode = 755
read list =john,lexi,rathi
write list =@groupa,@groupb,@groupc
valid users = @work,@Developer,@support
read only = no
---------------------------------------------------

Members in Groups
groupa = shashi, thomas, kiran, mathew, rosh
groupb = rakesh, william, randy, john, lexi, rathi
groupc = simsim, aham, gothik, rama, ruby
---------------------------------------------------

all these groups have read/write permission on above share only john, lexi and rathi have read permissions.
--------------------------------------------------

I thought adding john, lexi and rathi to read list would restrict them from writing to share but it doesn't happen.

please help as early as possible or guide me to the place where I can find the help for same. As I have tried to find samba forums but wasn't able to find the appropriate.

Look at what you are doing. John, lexi, and rathi are in groupb. For the write list, you include group b, yet for the read list you are using individual users. You will need to create either a separate group for the users, or remove group b from the write list and manually list the users.