Backup Restore The purpose of backup is to

Backup & Restore • The 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.

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

Proper Backup Procedure • • Choose your application Scheduling Implementation Inventory (content and media) Verify Automate Secure

Factors • Determine which data is critical. • Determine frequency and types of backups to be used. – Full – Differential – Incremental

Factors • Determine which data is static and which is dynamic. – Some OS installations are changed infrequently; few backups required – E-commerce may require continuous backups. – Understand the changing state of your client’s data to determine an appropriate backup sched. – Organize with partitions

Factors • Determine the appropriate media storage for your backups: – CD – DVD – Tape – Disk – Solid State?

Factors • Partitioning of disk space is used to manage backups

Choose your Backup App • Mac OS X : – Time Machine • Linux/Unix : – tar (tape archive), cpio, dump • MS Windows : – MS Windows XP & 7 includes Backup & Restore capability – Many commercial apps are available

Enterprise Level Backup Apps • Paragon Backup & Recovery includes customer support • Backup 4 All Professional • GRBack. Pro 7

Schedule • Determine the categories of data so you can schedule the backups accordingly

Schedule • Partitions are often used to manage backups • Examples: – The OS has its own partition and may require infrequent backups if changes are quarterly – User data may require nightly backups – Users must know what partitions have backup and the frequency (SLA).

Schedule • Full Archival Backup – image backup implies copying the unused space. • Differential Backup – what has changed since the last backup • Incremental Backup – what has changed since the last backup of anytype

Full Archival Backup • Mirror – every last bit on the disk is duplicated. • Many full backups ignore empty space.

Full Archival Backup (Pros) Pros • Provides a complete copy of data • Easy 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) Cons • Usually requires more media space than either differential or incremental. • Takes a long time to recover the full backup to a new disk.

Full Archival Backup • Consider making multiple backup copies • Full backup media should be stored offsite to protect data from disasters – Fire, Flood, Earthquake, Terrorist attack, Sabotage, Hacker attacks

Full Archival Backups • The 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 Backup • Copy 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) • Redundancy • Usually 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 Backups • A 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 Backups • Pros – Keeps a revision history of actively changing files – Fastest backup type – Uses the least amount of media to complete a single backup • Cons – Much more difficult to manage

Schedule Example • Full backup twice per year • Differential each first Saturday morning of each month that is not scheduled for a full backup • Incremental each Saturday morning that is not scheduled for a Full or Differential

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

The Actual Backup • Assignment of responsibilities – Written in the SA’s job description • Acceptance of accountability – A signed form indicating that the backup was complete, verified and secured

The Actual Backup • Hardware – Choose the media type – Centralize the backup to reduce redundancy of hardware – Not everyone archives the local “C-Drive” on general purpose workstations. (SLA and user awareness)

Backup Inventory • Inventory the backup media – Tapes and other writable media use barcodes or hand-written labels • Inventory the content of the media – The backup should have a table of contents included in the backup

Backup Inventory • The media label information: – Date – System identifier – Partition name(s) – Backup category: full, differential, incremental

Verify • The 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: Firedrills • When 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 scheduling • Linux/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 Backup • Offsite storage • Encryption: to encrypt or not to encrypt, … – Will the encryption key always be available? – Statute or contract (SLA) may require encryption

Secure: Off-Site Storage Off site storage has risks all its own – Data can be lost/destroyed in transit – How important is it to have a backup of the backup? – Some backups can be kept on site

Secure: Example Strategy Where 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 Compression • Risks – 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 Backups • Contract to store your data in a “secret” offsite location. (Secret implies a need to know basis)

Backup Considerations • Backups slow down service. This should be included in the SLA – Files should be write-locked during backup. • Avoid doing backups during peak service hours. Schedule during early AM hours on the weekend and holidays.

Restore • Common reasons for restores – Accidental file deletion – Disk failure – Disaster recovery • Fire, flood, earthquake, hacker attack, sabotage, terrorist attack, etc.

Accidental File Deletion • If 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 Failure • A disk failure causes two problems – Loss of data – Loss of service • Critical 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 Tape • Restoring 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 Backup • Large amounts of data historically favored tape media for backup: – Tapes are portable and fairly durable.

Tapes • Tape 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 storage • Easy to transport • Some tape formats are more reliable than others.

Tape Inventory • Backup tapes must be – Properly labeled – Properly stored • Proper inventory is needed to do restores in a timely fashion. – Hand written labels are ok – Bar codes and printed labels are better.

Tape Inventory • Inventory 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 don’t want to purchase any more hardware than is needed.

Tape • Rotate media – Incremental backup stored on site can be reused.

Tape Standards • • • 8 mm DLT DAT (4 mm) QIC http: //www. pctechguide. com/15 tape. htm Imation. com

Tape Technology • Tape 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.

Firedrills • An occasional test of a full partition restore is not unreasonable. This would be done if – A 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.

Centralization • Without centralization, a tape drive is needed for each server location. • Equipment can be interchanged more easily when centralized.

High Access DB Backups • Some 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.

Technology • Disk 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 Procedure • • Choose your application Scheduling (know your data) The actual backup Inventory (content and media) Verify Automate Secure