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Virtual memory is a mechanism or system. This system deals with Virtual addresses from Virtual address space. Each process running under windows gets virtual memory addresses starting from 0 to 4,294,967,295 (2*32-1 = 4 GB), no matter how much RAM is installed on the system.

That is; each user process typically has 4gb virtual address space (VAS). User process could see only the VAS area, which will in turn map to physical memory. Virtual memory address makes the user process to think in such a way that at any point in time, user process can address more memory than the physical memory(RAM) available in the system. Also the user process will have the impression that all the memory it deals with are contiguous.

The map between the virtual address & physical memory is done using page table entries(PTE). Each user process will have a page table which is an internal data structure translate virtual address to its corresponding physical address. The page table tells the process where the page is stored, whether in the disk or in the ram. PTE are present in the main memory.

PTE will have the information, where the page is available. ie., whether the page is available in the disk of physical memory. If the page is not loaded into memory, the loaction of disk will be there in the PTEs.

If the page has to be loaded, a hard page fault will be triggered & the page will be loaded to the memory(ram). Once the page is in the RAM the PTE is updated to reflect the page frame number/location.

Here is a useful link from SQLTeam on sql server versions,fixes & patches till date. The link is so perfect since the page is updated on a regular basis by author Bill Graziano.

http://www.sqlteam.com/article/sql-server-versions

Error Defined

[Microsoft SQL-DMO (ODBC SQLState: 42000)] Error 1934: [Microsoft][ODBC SQL Server Driver][SQL Server]DBCC failed because the following SET options have incorrect settings: ‘QUOTED_IDENTIFIER, ARITHABORT’.

Description 

This problem occurs when a job is created after you create a maintenance plan using maintenance wizard.

Solution

To work around this problem, add the -SupportComputedColumn parameter to the command that is included in the first step of the following job: Optimizations Job for DB Maintenance Plan ‘DB Maintenance Plan name’

EXECUTE master.dbo.xp_sqlmaint N’-Plan -WriteHistory -CkDB -SupportComputedColumn’

The -SupportComputedColumn parameter is a new feature that was introduced in SQL Server 2000 Service Pack 4 (SP4).

Follow the below guide lines when changing/selecting an SQL Server or SQL Server agent service account.

Make sure to change the service account from Enterprise Manager(SQL 2000) or Configuration manager
(SQL 2005). If we change from the services.msc panel, it will not update certain details like windows user
rights, registry rights & file system rights, which may create issue like sql or agent not starting.

Also note that , its always better to have 2 domain service accounts , 1 domain account for sql server with local system privilege
& 1 for sql server agent with local system admin privilege.
For SQL Server 2000 use Enterprise Manager , follow the guide lines

1) Open Enterprise Manager
2) Right Click in the sql server -> Properties

3) Go to Security tab, in the Startup service account, give the new service account & click ok

Also for changing the service account for SQL Agent,

1) Management -> SQL Server Agent, right click Properties

2) Modify the Service starup account & click ok

For SQL Server 2005, follow the below guide lines
1) Start SQL Server Configuration Manager.

2) Select SQL Server 2005 Services in the pane on the left.

3) In the pane on the right, select the service whose account you want to alter, right-click,
and select Properties -> Logon tab.

4) Change the account & click apply