BACKUP & RESTORE
The purpose of backup is to protect
data from loss.
The purpose of restore is to recover
data that is temporarily
BACKUP
To backup or not to back up,
that is the question.
Backup is not free.
No backup is risky.
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FACTORS OF A PROPER BACKUP
Planning
Scheduling
Backup operation
Inventory (content and media)
Verifcation
PLANNING
Choose your backup app.
Determine which data is critical.
Determine frequency and types of
backups to be used.
Archival (mirror or image)
Diferential
Incremental
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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.
PLANNING
Determine the appropriate media
storage for your backups:
CD
DVD
Tape
Disk
Solid State?
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SCHEDULE
Full Archival Backup
Mirror backup
image 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
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FULL ARCHIVAL BACKUP
Provides a complete copy of
data
Easy to manage:
Done less frequently than other
types of backups :
FULL ARCHIVAL BACKUP
Consider making multiple backup
copies
Full backup media should be stored
ofsite to protect data from:
Fire
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,
DIFFERENTIAL BACKUP (PROS)
Redundancy
Usually takes up less time and space than a full backup.
If the diferential backup grows to the size of the last full
backup, then schedule a new full backup.
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DIFFERENTIAL BACKUP (CONS)
Redundancy – potentially many unneeded copies of the same
data (also a potential pro)
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.
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INCREMENTAL BACKUPS
Pros
Keeps a revision history of actively changing fles
Fastest backup type
Uses the least amount of media
Cons
BACKUP INVENTORY
Inventory the backup media
Tapes and other writable media use barcodes and labels
Inventory the content of the media
The backup may require a table of contents
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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
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.
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BACKUP AUTOMATION
Non automated backups are
dangerous.
Automation reduces human errors.
Choose your app for backup
Carbon Copy Cloner
Macrium Refect
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?
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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!
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)
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BACKUP ADDENDUM
Backups slow down service.
Files are write-locked during
backup.
RESTORE
Three reasons for restores
Accidental fle deletion
Disk failure
Disaster recovery
Fire, food, earthquake, hacker
attack, sabotage, terrorist attack,
etc
.
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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
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.
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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
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.
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TAPE TECHNOLOGY
Tape technology expands in
leaps.
Tape hardware purchases are
not made on a constant basis
(like disk storage).
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
.
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