Re: BAST in RAC

K Gopalakrishnan wrote:

>In RAC the lock related operations are handled by Global Enqueue
>Services (GES) layer. Asynchronous System Traps (AST) are just like
>generic interrupt service routine. There are two types of interrupts
>or ASTs in the RAC. One is AAST (Acquisition AST) and another one is
>BAST (Blocking AST).This will be visible in the X$ structure X$LE
>(Lock Element?)
>
>When a process wants to acesss a resurce in RAC environment it needs
>to acquire lock and this will be given by GES. Before granting the
>lock to the process, GES will send the global AST to the holder of
>that resource and the
>holder may grant access to the requesting process. Once you have got
>the required locks on that resource GES will send an another AST
>(AAST) to tell that you have aqcuired the lock.
>
>GES will have the queue of requests/converts and will be delievering
>AST on an ongoing basis. BAST is the special kind of interrupt
>(Blocking AST) that will be sent to the process holding the resource
>that may lead some conflicts in the request conversions.
>
>
>

Aaaargh! I see that RDB gang has exercised some terminological influence over the
rest of Oracle Corp. Those entities are NOT like interrupts. They're implemented
through TCP control sockets and signals. Using the terminology from another CPU
and another OS is confusing as hell. Somebody probably wanted to look smart, so
they used those words without explanation or definition. If Oracle picked RDB and
some terminology from the late DECosaurus Rex, it would be also nice to pick a habit
of providing decent documentation as well. AST is something closely related to
certain processor architecture and certain OS. Oracle is using those terms, so that
people can pretend to be "experts". Whenever some oraclite mentions AST's in my presence, I make sure that the experience isn't easily forgotten. Your description of AST is what is scientifically known as mumbo-jumbo (Oracle* Mumbo-Jumbo 10g) and makes no sense whatsoever. RAC processes work over TCP sockets and do not "deliver interrupts". Processors and hardware devices
deliver interrupts. Sockets deliver packets. If you want to provide internal information,
please do it properly and not in a sloppy and misleading way using incorrect and undefined terminology. This is the same comment that I've sent in private email to Steve Adams when he was talking about "ASTs" in his internals book.

-- 
Mladen Gogala
Oracle DBA
Ext. 121


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