Backup & RestoreThe purpose of backup is to protect data from loss.The purpose of restore is to recover data that is temporarily unavailable due to some unexpected event.

BackupTo backup or not to back up, that is the question.Backup is not free.No backup is risky.

Proper Backup ProcedureChoose your applicationSchedulingImplementationInventory (content and media)VerifyAutomateSecure

FactorsDetermine which data is critical.Determine frequency and types of backups to be used.FullDifferentialIncremental

FactorsDetermine which data is static and which is dynamic.Some OS installations are changed infrequently; few backups requiredE-commerce may require continuous backups.Understand the changing state of your clients data to determine an appropriate backup sched.Organize with partitions

FactorsDetermine the appropriate media storage for your backups:CDDVDTapeDiskSolid State?

FactorsPartitioning of disk space is used to manage backups

Choose your Backup AppMac OS X : Time MachineLinux/Unix : tar (tape archive), cpio, dumpMS Windows :MS Windows XP & 7 includes Backup & Restore capabilityMany commercial apps are available

Enterprise Level Backup AppsParagon Backup & Recovery includes customer supportBackup4All ProfessionalGRBackPro7

ScheduleDetermine the categories of data so you can schedule the backups accordingly

SchedulePartitions are often used to manage backupsExamples:The OS has its own partition and may require infrequent backups if changes are quarterlyUser data may require nightly backupsUsers must know what partitions have backup and the frequency (SLA).

ScheduleFull Archival Backupimage backup implies copying the unused space.Differential Backup what has changed since the last backupIncremental Backup what has changed since the last backup of anytype

Full Archival BackupMirror every last bit on the disk is duplicated.Many full backups ignore empty space.

Full Archival Backup (Pros)ProsProvides a complete copy of dataEasy to manage: Done less frequently than other types of backups due to cost and resource requirements: Monthly, Quarterly, semi-annually, annually.

Full Archival Backup (Cons)ConsUsually requires more media space than either differential or incremental.Takes a long time to recover the full backup to a new disk.

Full Archival BackupConsider making multiple backup copiesFull backup media should be stored offsite to protect data from disastersFire, Flood, Earthquake, Terrorist attack, Sabotage, Hacker attacks

Full Archival BackupsThe trend is to reduce the cycle of full backups. This is because of liability. Files that are not backed up cannot be subpoenaed.Statute may require destruction of some records.

Differential BackupCopy files changed since the last full backup.Differential backups grow with time. They can eventually grow larger than the last full backup.Scheduled less frequently than a full backups: Weekly, monthly.

Differential Backup (Pros)RedundancyUsually takes up less time and space than a full backup.If the differential backup grows to the size of the last full backup, then schedule a new full backup.

Differential Backup (Cons)Redundancy potentially many unneeded copies of the same data.Subsequent differentials take longer and use more media space.

Incremental BackupsA backup of what has changed since the last previous backup of any type.Frequency of incremental backups depends on the client needs.Weekly, daily, hourly, continuously.

Incremental BackupsProsKeeps a revision history of actively changing filesFastest backup typeUses the least amount of media to complete a single backupConsMuch more difficult to manage

Schedule ExampleFull backup twice per yearDifferential each first Saturday morning of each month that is not scheduled for a full backupIncremental each Saturday morning that is not scheduled for a Full or Differential

Other Schedule ConsiderationsConsider completing a backup in conjunction with and before any major system changes are scheduled.

The Actual Backup

Assignment of responsibilitiesWritten in the SAs job descriptionAcceptance of accountabilityA signed form indicating that the backup was complete, verified and secured

The Actual BackupHardwareChoose the media typeCentralize the backup to reduce redundancy of hardwareNot everyone archives the local C-Drive on general purpose workstations. (SLA and user awareness)

Backup InventoryInventory the backup mediaTapes and other writable media use barcodes or hand-written labelsInventory the content of the mediaThe backup should have a table of contents included in the backup

Backup InventoryThe media label information:DateSystem identifierPartition name(s)Backup category: full, differential, incremental

VerifyThe only time you know the quality of your backup media is when you are doing a restore.This is the worse time to discover you have problems.Restore a small subset of random files from the backup. Verify their integrity through differences or checksums.

Verify: FiredrillsWhen new equipment arrives, test your backup procedure on the new equipment to verify it works correctly

Backup Automation

Automation reduces human errors.Many pre-packaged apps include automatic schedulingLinux/Unix backup scripts can be submitted using the cron utility. Logs can be kept in /var/log, and e-mail can be sent to the admin.

Secure The BackupOffsite storageEncryption: to encrypt or not to encrypt, Will the encryption key always be available?Statute or contract (SLA) may require encryption

Secure: Off-Site StorageOff site storage has risks all its ownData can be lost/destroyed in transitHow important is it to have a backup of the backup?Some backups can be kept on site

Secure: Example StrategyWhere the backup is stored will impact service response to restore requests:Consider keeping incremental backups on site.Differential and full backups could be stored offsite.

Data CompressionRisks if the media is damaged, recovery may be difficult or impossible.Lossy some data tolerates degradation (loss of information)No-loss Some data should not be compressed. Know your data!

Secure BackupsContract to store your data in a secret offsite location. (Secret implies a need to know basis)

Backup ConsiderationsBackups slow down service. This should be included in the SLAFiles should be write-locked during backup.Avoid doing backups during peak service hours. Schedule during early AM hours on the weekend and holidays.

RestoreCommon reasons for restoresAccidental file deletionDisk failureDisaster recoveryFire, flood, earthquake, hacker attack, sabotage, terrorist attack, etc.

Accidental File DeletionIf backups are once per day, lost work is limited to one day for a given file. (RAID does not help)As storage technology gets cheaper by the Gbyte, it becomes easier to implement more sophisticated storage procedures that are more timely. (HDD backup).A user wants the restoration to be immediate. The quicker the turnaround, the happier your customer.

Disk FailureA disk failure causes two problemsLoss of dataLoss of serviceCritical systems should implement RAID so that disk failures do not cause a loss of service.Restoring an entire disk is slow. Service is hampered until the last bit is recovered.Consider using hot spares and hot swap

Disk Restore from TapeRestoring from tape can interrupt service.Restoring from tape slows the restore process by a factor of about 5-10 times compared to a simple disk to disk copy.

Tape BackupLarge amounts of data historically favored tape media for backup:Tapes are portable and fairly durable.

TapesTape historically has been the preferred backup media for very large data storage environments.Tape has a useful life span.Tape can be very robust for storageEasy to transportSome tape formats are more reliable than others.

Tape InventoryBackup tapes must be Properly labeledProperly storedProper inventory is needed to do restores in a timely fashion.Hand written labels are okBar codes and printed labels are better.

Tape InventoryInventory is not limited to the physical tape itself.The contents of tapes must be inventoried.The number of accesses must be logged because tapes ware out.

Tape equipment is not free. You dont want to purchase any more hardware than is needed.

TapeRotate mediaIncremental backup stored on site can be reused.

Tape Standards8mmDLTDAT (4mm)QIChttp://www.pctechguide.com/15tape.htmImation.com

Tape TechnologyTape technology expands in leaps.Tape hardware purchases are not made on a constant basis (like disk storage).Tape technology is purchased in leaps. Three year intervals are more practical.

FiredrillsAn occasional test of a full partition restore is not unreasonable. This would be done ifA change is made in the backup software release.A change of vendor for the backup software product.When a new server with new unused disk arrives.

CentralizationWithout centralization, a tape drive is needed for each server location.Equipment can be interchanged more easily when centralized.

High Access DB BackupsSome data changes so rapidly that backups are not practical.RAID 1 mirroring may be the only practical solution.RAID 1+1, includes a second mirror in a RAID 1 array.

TechnologyDisk space cost drops by 1/2 about every 18-24 months.Disk space is filled as it expands.Disk requirements are increasing on a continuous basis.Disk budgets increase faster than tape backup budgets.

Backup ProcedureChoose your applicationScheduling (know your data)The actual backupInventory (content and media)VerifyAutomateSecure