Hi all,
The "sun cluster white paper" have a picture in the desicription. I have some
question,from the picture , I can't figure out what is the process of replica.
question1: in step 1, what is the "transfer commit"of"request + transfer
commit" means, and what is the "+" means.
question2: in step 6,why use the dot line and send confirm to secondary? in my
mind , the client should send it to primary ,because secondary is offline from
the client's aspect.
question3:in the step 5, why the primary need "+ confirm" ? replay means
confirm already.
based on my understanding, i think the replica will work like this:
1/client send a request to primary.(+transfer commit means need commit,yet i
don't know why transfer commit yet not only commit?)
2/primary do checkpoint and then send it to secondary.
3/secondary receive checkpoint and make confirm to primary
4/primary receive commit and then continue to response to the reply, and keep
the force log for the steps.
5/after finish , send client a reply with a flag to tell client to response the
confirm to himself or secondary(no link to primary,do primary don't need the
confirm. how client send confirm to secondary ,and secondary is offline,so why
send to secondary?)
In my mind , I think this picture only fit for one special kind of service.yet
I really do need to know whether the process is right and what is the impaction
from the picture should be.
the checkpoint struction in code shows it contain
replica::ckpt_seq_t minseq;
replica::ckpt_seq_t value;
So I am wonder how to use this two values?
Thanks
Edward
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