dtc

Orphaned MSDTC transactions (-2 spids)

SPIDS with a value of -2 Any dba looking after a server that takes part in a distributed transaction will probably have come across situations where a SPID that does not show up in master..sysprocesses or sys.dm_exec_sessions (depending on your version of SQL Server) ends up blocking other users. Looking at sp_lock or the syslockinfo table or sys.dm_tran_locks would show resources being locked by a SPID with a value of -2.