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• Backup is a key element in any Business Continuity Plan.
• Backups are important because of the possibility of a disaster, hardware failure, and storage media failure, which can lead to data loss.

3-2-1 Backup Strategy

• The 3-2-1 backup strategy involves creating three copies of data: One primary and two backups.
• Copies should be stored on at least two types of storage media such as local drive, network share/NAS, tape drive etc.
• One copy should be stored offsite, such as in the cloud.

Backup Media

• HDD/SSD: Hard Disk Drives and Solid-State Drives can be used, ranging from internal disks to NAS.
• Removable media such as tape, thumb drives, portable hard disks, mobile phones, and smart devices can be used.
• Optical media like CD-R/RW, DVD-R/RW, and Blu-Ray (BD-R/RW) are options.
• Cloud storage options include Amazon S3, Dropbox, Box, Microsoft One Drive, and Google Drive.

Backup Site

• An onsite backup is stored locally in the same location as the original data.
• An off-site backup is stored in a different location, involving network or physical delivery.
• Republic Poly, for example, has an off-site backup in Nanyang Poly.

Cloud Backup

• Many products offer features like data compression, encryption, and offline backup.
• File retention policies and versioning can be based on customer requirements.
• Redundancy is achieved through multiple copies at different locations.
• A centralized management console for IT administrators enables easy management.
• Cloud elasticity means automated storage space increases

Cloud Backup Service Providers

• Example providers include Acronis Backup Cloud, Backblaze Business Backup, Carbonite Safe Core Computer Backup, Dropbox Business, Google Drive Enterprise, and Microsoft OneDrive for Business.

Backup Types

Full Backup

• Full backups involve a complete and comprehensive backup of all files on a disk or server.
• Data is current only at the point of backup, and this can be a time-consuming process.
• Restoration is the fastest with full backups

Incremental Backup

• Incremental backups are partial that store information changed since the last full or partial backup.
• For example, if a full backup is done on Monday,Tuesday's incremental backup will only contain information changed since Monday.
• The fastest to perform, but slow to restore.

Differential Backup

• Differential backups are similar to incremental backups but back up files altered since the last full backup.
• Monday night full backup, then Tuesday night differential backup stores changes on Tuesday, and Wednesday differential backup stores changes on Tuesday and Wednesday.
• The size and time needed increases as they are performed, these are faster to restore than incremental backups.

Backup Restoration Example

• XYZ company does daily backups from Monday to Sundays. If the server crashes after the entire week's backup, then restoring data is possible depending on its type.
• With Full Backups, simply restore the latest full backup
• With Full + differential backups, restore the latest full backup and then the most recent differential backup
• With Full + incremental backups, restore the full backup, and then all the incremental backups in order

Things to consider for Backup

• Consider how big the data to be backed up is, whether it should be all files and folders, or selected files only.
• Backup media could be BluRay, up to 100GB (BD-R XL).
• Backup media could be TAPE, up to 18TB (LTO-9 cartridge uncompressed), with future generations exceeding 300-500TB (LTO-12 and beyond).
• Is the chosen media fast enough, noting tapes are slower but have high capacity
• Remote backups are slow, with Internet, but faster via private network as SAN transfer bandwidths using Fibre Channel have 16 to 32 Gbps
• Ensure that the restore is fast enough. Systems may not be operable until restore is complete.
• If the restore time is slow it may not be suitable for time-critical application such the Singapore Stock Exchange
• Establish the media rotation and backup horizon, being how long should the backup data be available?, example 1 week, 1 month, 1 year?
• Cost; fast and high-capacity drives cost more money, SAN is expensive while TAPE is cheaper and DVD is the cheapest
• Security is important, only authorized personnel should be allowed to perform backup operations and have access to the backup data
• Physical access to the backup media has to be tightly controlled with the option to encrypt data before writing

Continuous Monitoring & Automation Strategies

• Automate the backup operations by
  • Using scripts, such as scheduled backup scripts
  • Courses of action for different scenarios, such as power failure or faulty backup
  • Snapshots, both scheduled or ad-hoc
  • Cloud storage elasticity; automatic increase of storage space according to backup needs
• Continuously monitor operations by
  • Monitoring the backup logs
  • Automated event handling or notifications being triggered by alerts
  • Monitoring remote backups
  • Monitoring external storage such as Network Attached Storage (NAS)
  • Monitoring RAID storage system
• Data is an important asset and requires protection; lawsuits happen if there is loss and leakage, failure to comply with law and storage regulations
• Use backup and RAID to improve integrity and availability
• Encrypt to provide better confidentiality and integrity

Storage Redundancy

• Hard Disk Drives (HDDs) are a commonly-used magnetic storage type that has large capacities up to 16/18/20 TB
• Solid State Drives (SSDs) use non-volatile (NV) NAND flash memory chips but have lower capacity and limited write lifespan.
• SSDs are often used when speed is critical, HDD's are used for backups.

Storage Drive Failure Causes:

• Due to wear and tear
• Manufacturing defects
• Software bugs or malware

RAID

• RAID (Redundant Array of Independent Drives) is a technology that provides increased storage functions and reliability through redundancy.
• This is achieved by combining multiple disk drive components into a logical unit.
• Data is distributed across the drives in several ways. Some ways are called RAID levels.
• Common RAID levels are RAID 0, RAID 1, RAID 5, and RAID 6

RAID 0

• RAID 0 involves a striped disk array without fault tolerance or redundancy.
• A single chunk of data is spread across multiple drives, which improves performance.
• The minimum is 2 drives to implement, if one disk fails, all of the data will be lost.
• There is great performance in read and write operations since there is no overhead caused by parity controls, and all storage capacity can be used, the technology being easy to implement
• There is no fault-tolerance and should not be used on mission-critical systems, ideal for non-critical storage of data that have to be read/written at high speed

RAID 1

• RAID 1 involves mirroring where the content of 1 hard disk is copied to the other hard disk in real time.
• If one hard disk crashes, the other can be used, containing all the up-to-date data
• There is excellent read-speed and a write-speed that is comparable to that of a single disk.
• If a disk fails, data does not have to be rebuilt: it just needs to be copied to the replacement disk. Effective storage capacity is only half of the the total disk.
• Software doesn't always allow a hot swap of a failed disk. Therefore, it is ideal for mission critical storage but only when there are two disks.
• When more than 2 disks are used the storage may remain 50% of the total disk capacity or may decrease depending on the configuration

RAID 5 & 6

• These rely on striped sets
• RAID 5 uses distributed parity; minimum 3 disks
• If one disk crashes, a new blank disk can be inserted without shutting down the server.
• The new disk has its content built-up based on information in the other disks and is known as hot swapping
• RAID 6 is striped disks with dual partity, similar to RAID 5 except that it can recover from loss of TWO disks
• Read data transactions are very fast while write data transaction are somewhat slower due to the parity
• Disk failures have an effect on throughput, and this is a complex technology, but a great all round system for efficiency, security and performance. It is also ideal for files and applications.
• The storage efficiency of RAID 5 and RAID 6 configurations increases with an increase in number of disks used.
• For example; when 4 disks are used in a RAID 5 configuration, storage efficiency will increase from 75% to 80% with 5 disks. When 4 disks are used in RAID 6, storage efficieny increases from 50-60% with the addition of a 5th drive.

Problem with RAID

• RAID will not provide any protection for data corruption
• Example; If database file is corrupted, RAID will replicate the corruption to the other drives - both will have corrupted data
• Capacity is less than the max capacity.
• Mirroring only has 50% capacity since one disk is a copy of the other and RAID 5's parity occupies the space equivalent to one disk
• RAID 5 can only afford one disk to fail, while RAID 6 can afford up to two disks, consuming more space for parity information

Proposed Improvement (Solution)

• Backup should use the 3-2-1 strategy.
• Use media rotation schemes like differential and incorporate off-site backup in case of a cataclysmic event.
• Utilize off-site cloud storage should remote backups occur
• Remote server backup and incorporate automation and continuous monitoring
• Come up with company-wide policy on data storage and backup