Tempb db size identification

Question

Hi,
    There is version store size counter in transaction category of performance monitor
, and there is
version_store_reserved_page_count col in
dm_db_file_space_usage
Q1) I wanted to know how should i compair/diffrencate them.
Q2) Please also tel me what is version store unit count in transaction category of counters of performace monitor.
yours sincerley

Answer 1

what is version store unit?
Q3) "When tempdb runs out of space, the Database Engine forces the version stores to shrink."
above was written in following link
http://technet.microsoft.com/en-us/library/ms175492(v=sql.105).aspx
Does that mean shrinking is done automatically for other stores like object, internal objects etc in tempdb.
but fially i have to shrink manually. Please explain
Q4) i have made a job(runs every 10 sec) and collected data from few miniuts in a table
to find the tempdb max usage , so that i can increment the auto grow accordingally.
please tel me is it correct.
select
(max((user_objects_alloc_page_count-user_objects_dealloc_page_count)
+
internal_objects_alloc_page_count
-internal_objects_dealloc_page_count)
* 8
* 1.0/128
from
tempdm_db_task_space_usage
yours sincerely