Business Continuity and Disaster Recover Pertemuan 11
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. FACTORS OF A PROPER BACKUP
- Planning Scheduling Backup operation
- Inventory (content and media)
- Verifcation Automation Security
Determine which data is critical. Determine frequency and types of backups to be used.
Archival (mirror or image)
Diferential Incremental
PLANNING Determine which data is static and which is dynamic.
The OS and apps tend to be static; few backups required
E-commerce transactions may require continuous backups.
Understand the changing state of your client’s data to determine an appropriate backup sched.
Organize with partitions
PLANNING Determine the appropriate media storage for your backups:
DVD Tape
CD
Disk Solid State?
SCHEDULE Full Archival Backup
Mirror backup
image backup Diferential Backup Incremental Backup
FULL ARCHIVAL BACKUP
Formatted into a single file and stored on your media choice.
Mirror– every last bit on the disk is duplicated including empty space.
Image - empty space is ignored
FULL ARCHIVAL BACKUP
Provides a complete copy of data Easy to manage:
Done less frequently than other types of backups : Monthly, Quarterly, semi- annually, annually.
FULL ARCHIVAL BACKUP
Consider making multiple backup copies Full backup media should be stored ofsite to protect data from: Fire
Natural disasters (food, earthquake, etc)
Terrorist attack
Sabotage
Hacker attacks
DIFFERENTIAL BACKUP
Copy the fles changed since the last full backup. Diferential backups grow with time. They can eventually grow larger than the last full backup. Scheduled less frequently than a full backups: Weekly, monthly.
Redundancy DIFFERENTIAL BACKUP (PROS) If the diferential backup grows to the size of the last full Usually takes up less time and space than a full backup. backup, then schedule a new full backup.
Redundancy – potentially many unneeded copies of the same DIFFERENTIAL BACKUP (CONS) Subsequent diferentials take longer and use more media space. data (also a potential pro)
INCREMENTAL BACKUPS Frequency of incremental backups depends on the client needs. Weekly, daily, hourly, continuously. of any type.
A backup of what has changed since the last previous backup
INCREMENTAL BACKUPS Uses the least amount of media Fastest backup type Keeps a revision history of actively changing fles
Pros
Cons Much more difcult to manage
Inventory the backup media BACKUP INVENTORY Inventory the content of the media Tapes and other writable media use barcodes and labels
The backup may require a table of contents
VERIFY: FIREDRILLS
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. Pick random fles from a backup and restore them.
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.
BACKUP AUTOMATION
Non automated backups are dangerous. Automation reduces human errors. Choose your app for backup Carbon Copy Cloner
Macrium Refect Tar, cpio, dump, dd
SECURE: OFF-SITE STORAGE
Of 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?
DATA COMPRESSION
Risks – if the media is damaged, recovery may be difcult or impossible. Lossy compression is not suitable for many kinds of
data. OK for images, video, or
sound. Know your data!No-loss compression for data base fles, applications, etc.
BACKUP COMPRESSION & ENCRYPTION Compression saves space Encryption provides security Lost encryption keys make recovery impossible Some damaged media can be partially recovered. Consider a Mirror Archive (no compression or encryption)
BACKUP ADDENDUM Backups slow down service.
Files are write-locked during backup.
Backups should not be done during peak service hours. Schedule during early AM hours on the weekend.
RESTORE Three reasons for restores
Accidental fle deletion
Disk failure
Disaster recovery
Fire, food, 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 fle. (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. (Mirror backup). A user wants the restoration to be immediate. The quicker the turnaround, the happier your customer.
TAPES Tape is (or was?) 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 tansport 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 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
CENTRALIZATION Costs can be reduced through centralization
Tape mounts are labor intensive, so look to automation. Con
No need for hardware or manpower duplication
Equipment can be interchanged more easily when centralized .
TECHNOLOGY Disk space cost drops by 1/2 about every 18-24 months. Disk space is flled as it expands. Disk requirements are increasing on a continuous basis. Disk budgets increase faster than tape backup budgets.