Avoiding Data Loss

Tape Backup

Method	Description
Full Backup	backs up and marks selected files, whether or not they have changed since the last backup
Copy	backs up selected files without marking them as backed up
Incremental Backup	backs up and marks selected files only if they have changed since the last backup
Differential Backup	backs up selected files only if they have changed since the last backup w/o marking them as backed up

The difference between Incremental and Differential IF => Incremental Fast to backup; Slow to Restore   => Marks files as backed up     => Differential Slow to backup; Fast to Restore

UPS

• power source to run the server for s short time
• safe shutdown management service
• prevent any more users from accessing the server
• send an alert message to the network admin.
• power is restored while UPS is active, the UPS will notify users that the power has returned

Fault Tolerant Systems - Windows NT supports Raid 0,1 and 5. For the exam, worry only about them.

• RAID 0 - disk striping
• disk striping divides data into 64k block and spreads it equally in a fixed rate and order among all disks in an array
• NOT FAULT  TOLERANT
• RAID 1 -
• disk mirroring - actually duplicates a partition and moves the duplication onto another physical disk
• disk duplexing - is a mirrored pair of disks with an addition disk controller on the second drive
• The only RAID solution that can house the system files in the Boot partition
• RAID 4 - disk guarding
• one drive is a dedicated parity drive, data is striped to multiple drives and then its parity sum is calculated, which is written to the dedicated parity drive
• works best for large block operations
• RAID 5 - striping with parity
• data is striped across multiple drives and then its parity sum is calculated, which is also striped across multiple drives (not a dedicated parity drive)
• sector sparing - hot fixing
• automatically adds sector - recovery capabilities to the file system while the computer is running
• 
  if bad sectors are found during disk I/O, the fault tolerance driver will attempt to move the data to good sector and map out the bad sector - only for SCSI, not ESDI or IDE