Security requirement for SharePoint backup shared folder

STSADM command is the only tool available when scheduling a SharePoint catastrophic backup. And this command requires a shared folder to store backup files. It's essential to setup appropriate permissions for this folder in order to have a successful backup run. From what I have done in our environment, the following accounts need modify (or change) permissions:

1. The account configured to run the Windows scheduled backup task
2. The moss farm account - this is the account used to run SharePoint jobs and Central Administration application pool.
3. The account for SQL Server services.
4. The Sql Server computer account. It's the Sql Server server name with a $ sign. For example, if your server name is sqlserver1, then the account name is sqlserver1$.

The same account permissions need to be configured for Sharing Permission, and Folder permission in Windows explorer.