This document discusses NBackup and Backup strategies for Firebird databases. NBackup allows creating multiple incremental backups over time, taking up more disk space but enabling restoration to precise historical states. Backup is slower than NBackup but is still useful for tasks like database renewal. When database corruption occurs, restoration may fail due to logical data issues, so regular NBackup is recommended to minimize data loss risks.

1. NBackup and Backup:
internals, usage strategy and
pitfalls
Dmitry Kuzmenko,
IBSurgeon

2. About IBSurgeon
• Tools and consulting
• Platinum Sponsor of Firebird
Foundation
• Founded in 2002: 10 years of
Firebird and InterBase recoveries
and consulting
• Based in Moscow, Russia
www.ib-aid.com www.ibsurgeon.com

3. Simple statements
•The smaller – the faster
•How to make database less size?
• no_reserve ! Minus up to 30% of size
• only for read-only databases
• CORE-3957
• split data

4. Splitting data
• By tables – problems with complex SQL
•Tablespaces – we do not have this
• Replication
• By databases
• Execute statement on external
• Partial backup
• Some tables are read-only
• Full backup + partial backup
• Hard to restore all these together

5. Backups
• Speed
• DB - read, backup – write
• Protocol – services API is the fastest (3-4 times
from tcp)
• Can’t be stopped by terminating gbak
• Slower than sequential copy
• -v – read 34mb/sec, write 33mb/sec, 1 core 60%
• no –v - read 60mb/sec, write 56mb/sec, 1 core 100%
• If DB size > RAM, can cause RAM consumption on
Windows. Use 2.5.2.

6. IBBackupSurgeon

7. Restore
• Create db, fill metadata
•Transfer data
• Create indices
• Backup – read, db – write
• Read 56mb/sec, write 60mb/sec – equal to
backup speed
•Db – read, temp – write, read, db – write
•Usually 2-4 times slower than backup

8. Critical time
time
crush
Detect what happened
Trying to fix with gfix or FBFirstAid
backup
restore
Error on restore?

9. What you need to remember
• Database can be corrupted hardly, no
reason to fix (or will take too much time)
• Restore can fail, due to logical data
corruption (FK, PK, etc)
• Application sufficient data can be broken
• Corruption in most cases (99%) causes
data loss
• Each action may need to be run 2-3 times

10. NBackup
• Introduced in Firebird 2.0 (2005, 7 years ago)
• Fast as copying file
• 17gb – 4m 30sec, 67mb/sec source and target.
• 22gb – 1m 30sec on SSD, 262mb/sec
• Very rarely used
• Most still do not understand what is this and how
it works, and how to organize 0-1-2-3… level
nbackups
• Maybe, most feel comfortable to restore
yesterday’s backup on crush?

11. NBackup sample 1
• 50 users, 10 hours per day, 68k transactions per day, accounting
• hourly nbackup – 1-2 minutes, total nbackups – 40gb (year)
5700
25
120
220
0 2000 4000 6000
Size
level 3 hour
level 2 day
level 1 week
Database

12. NBackup sample 2
• 100 users, 12 hours per day, 224k transactions per day, stock
• hourly nbackup – 1-2 minutes
10000
300
800
1000
0 5000 10000 15000
Size
level 3 hour
level 2 day
level 1 week
Database

13. •0 month
• 1 week depend on month
• 2 day depend on week
• 3 hour
• 3 hour depend on day
• 3 hour
• 2 day
• 3 hour
• 3 hour
• …

14. Usual case
DB
restore
backup
FBK FBK
FDB
copy

15. Using nbackup
DB
NBK
level 0
FBK
FDB
restore
backup

16. Problems
• Needs a lot of disk space
• Problems with Classic in 2.0, 2.1 – 2.5.1
recommended
• FBDataGuard monitors:
• Delta size
• Delta age
• -d ON | OFF
• On – Windows default, OS cache turned off
• Off – Linux default, OS cache turned off
• Off on Windows and FB < 2.5.2 can cause RAM
consumption

17. Summary
• Backup – loosing importance due to slowness
and need to restore it
• Still good to “renew” DB, change page size, other
options, check logical structure
• Nbackup – fastest way to make copy of db
• Page damage can’t be detected, still need to
backup/restore
• Lot of space for data
• Ability to “restore” more precize state of db

18. Thank you!
• Questions?
• www.ib-aid.com
• support@ib-aid.com