Presentation by Rafał Gołąb <rafal.galab@codibly.com> Redundancy vs Backup vs Archiving Databases (MySQL, PostgreSQL, MongoDB), Data

1. High Availability
Redundancy vs Backup vs Archiving
Databases (MySQL, PostgreSQL, MongoDB), Data
Rafał Gołąb <rafal.golab@codibly.com>
Kraków, 19.02.2015r.

2. Agenda
1. Redundancy, backup, archiving theory
1. Motivation
1. Objectives
1. Solutions
1. RAID & Replication & Archiving Tools
1. MySQL Backup Tools (real examples)
1. Conclusions

3. Redundancy, backup, archiving theory
● Redundancy
- establishes a straight copy of an entire system, ready to take over if the original
system fails
● Backup
- create a second copy of data at specific points in time
- ideally keeping multiple historic copies
- must be consistent
● Archiving
- makes a primary copy of selected data with the aim of retaining data in the long-
term

4. Motivation
Murphy’s law: Anything that can go wrong, will go wrong.

5. Motivation
http://highscalability.com/blog/2014/2/17/how-the-aolcom-architecture-evolved-to-99999-availability-8.html

6. Objectives
● understanding how big is a problem
● sleep well
● extend knowledge
● know the differences
● increase data safety

7. What will can happen?
● location
● networking
● hardware
● operating system
● data storage
● app layer
What can we do?
● load balancing
● fail-over
● disaster recovery

8. Detailed problem solving
● DNS problems
- round robin
- low ttl
- gslb (dnsmadeeasy.com, akamai)
● HTTP problems
- HAproxy, nginx (LB algorithms)
- memcache servers
- failover ip addresses
● MAIL problems
- few MX servers
- LB SMTP servers
● DATABASES & STORAGE problems
- next part of presentation

9. RAID (Redundant Array of Independent Disks)

10. RAID 0 (stripping)
● Adventages
- read/write speed
- capacity
● Disadventages
- not fault-tolerant
2TB1TB1TB1TB

11. RAID 1 (mirroring)
● Adventages
- have a copy of data (N-1)
- fastest read
● Disadventages
- slow write
- capacity (max one smallest disk)
rebuild

12. RAID 10 (stripping + mirroring)
● Adventages
- have a copy of data
- fast read/write
● Disadventages
- need the same disk (capacity and speed)

13. RAID 5
● Adventages
- fast read like raid 0
- fault-tolerant (one disk)
● Disadventages
- slow write
- slow read/write during disk failture

14. RAID 6
● Adventages
- fault-tolerant (two disks)
- fastest read than one disk
● Disadventages
- cost

15. RAID
WHAT IS RAID?
!!! REDUNDANCY !!!

16. Replication

17. REPLICATION
WHAT IS REPLICATION?
!!! REDUNDANCY !!!

18. LVM (Logical Volume Manager)
● PV (phisical volume), VG (volume group), LV (logical volume)
- pvdisplay, vgdisplay, lvdisplay
- pvs, vgs, lvs
- pvcreate, vgcreate, lvcreate
- pvremove, vgremove, lvremove
- lvextend, lvreduce
● Adventages
- may extend after several physical disks
- supports resizing LV on the fly
- supports snapshots
● RAID + LVM = safe and flexible storage

19. LVM - snapshots
LVM snapshots allow for a consistent backup even if files are open during the backup. The
snapshot volume needs enough space to store changes that occur during the backup.
100GB
5GB
100GB

20. LVM
WHAT IS LVM?
!!! BACKUP SYSTEM !!!

21. MySQL Backup Tools (real examples)
● mylvmbackup
● xtrabackup
- no tables locks
- only for innodb
● mysqldump
- tables locks
- long time recovery
- for small databases

22. Archiving Tools
● cron
● tar + gzip
● rsync
● scp
● ...

23. Conclusions
● High Availability is complex problem and different on each organisation.
● The best practice when it comes to protecting your data is using all of
solutions (redundancy, backup and archiving) when possible.
● Redundancy isn’t backup
● Backup is more important than redundancy
● Using LVM is the best solution for preparation DBs backups

24. Thank you for your attention. Questions?
Rafał Gołąb
Linux System Administrator
E-mail: rafal.golab@codibly.com
Mob.: (+48) 506 514 543
www.codibly.com