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--- notes:data_security_principles_and_guidelines [2024/06/12 10:35] – created Nikita Kipriyanov
+++ notes:data_security_principles_and_guidelines [2024/06/19 12:35] (current) – Nikita Kipriyanov
@@ Line 4: / Line 4: @@
 It's often said "RAID is not a backup". But without further discussion, it's not totally clear why. The real reason, these technologies are, generally, designed to solve different kinds of disasters, and, generally, backup is more important.
-The purpose of the **RAID** is //to reduce the possibility of the **downtime** caused by storage hardware failure//. This is very precise and narrow definition, which is good. RAID originated in times when we used hard disks that are not very reliable, and the question of failure was not "if" but "when"; so the natural desire was to introduce some redundancy into the system *a priori* so it will survive (not fail, not even stop serving) a failure of one or few hard disks. The action of replacing failed disks can be then postponed to convenient time frame, or even performed on-line.
+The purpose of the **RAID** is //to reduce the possibility of the **downtime** caused by storage hardware failure//. This is very precise and narrow definition, which is good. RAID originated in times when we used hard disks that are not very reliable, and the question of failure was not "if" but "when". The natural desire was to introduce some redundancy into the system //a priori// so it will survive (not fail, not even stop serving) a failure of one or few hard disks. The action of replacing failed disks can be then postponed to convenient time frame, or even performed on-line.
 The purpose of the **backup** is //to reduce the possibility of the **damage to data** (often referred to as "data loss") caused by hardware malfunction, software bugs, human error or malicious actions, and natural catastrophic events//. This by far supersedes the limited protection to the data that is offered by the RAID, but it's use requires the downtime to retrieve the data from the backup media.
@@ Line 25: / Line 25: @@
 ==== Backup usability should not depend on the survival of the system that was backed up ====
-In case a backup client is lost completely, the backup is the only means to recover. Often this means, we need to backup some application configuration along with the data.
+In case a backup client is lost completely, the backup is the only means to recover. Often this means, we need to backup some application configuration along with the data, or the system image at some large intervals.
 ==== Backup usability should not depend on the survival of the backup system, only it's datastore / media set ====