Information Technology Reference
In-Depth Information
table 8.5
SlAs for Backup/recoery
Backup
Type
Backup
Frequency
Data Type
Retention
Media TTL
a
Normal
Incremental
Daily
1 week
360 cycles or 1 year
Normal
Full-W
Weekly
1 Month
156 cycles or 3 years
Normal
Full-M
Monthly
6 months
60 cycles or 5 years
Normal
Full archive
Quarterly
X years
20 cycles or 5 years
App-X log files
Full
Daily
1 month
360 cycles or 1 year
a
TTL is
time to live
and begins with first media use; destroy and replace
media after TTL expiration.
n
Quality metrics—Verify integrity and performance against compliance
requirements where compliance requirements define ideal operations.
Security—Provide security services and mechanisms to create, capture, trans-
port, store, recover, and dispose of data.
n
Testing may occur pre-backup and post-backup. Pre-backup tests verify the
media is capable of accepting the backup. Such tests may include a successful for-
mat step; format failure results in notification to replace media. Post-backup tests
include verification of backup process (i.e., no software errors) and verification of
data via subsequent read from backup media. Testing is typically automatic. Error
detection results in operator notification and manual intervention. Table 8.5 pres-
ents sample SLAs for backup and recovery.
The intent of the SLA parameters is to provide the highest assurance of quality,
accuracy, dependability, and recovery according to organizational downtime tol-
erance. SLAs should address frequency of backups, time of day to avoid conten-
tion with production activity, restrictions on system effects (e.g., availability), and
backup storage, transport, retention, and cycling of media. SLAs should also address
the need and frequency for off-site storage and obtaining backups from off-site stor-
age for recovery; e.g., an off-site storage facility that closes Christmas Eve through
January 2 is not much use to a data center having trouble processing retail receipts
and inventory during the holidays.
8.16.4.1
Strategy
Figure 8.16 presents a backup strategy decision tool. The axes focus on business
drivers of
recovery speed
and
risk tolerance
. The decision tool may expand to include
a variety of backup services and mechanisms that support each of the categories: file
copy, co-resident media, independent image, and off site.
