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Hello again,

following application scenario: (interal tests, Sybase 16)

We've two test systems (virtual machines), one with VMWare, one with Hyper-V. In each of the database we've a size about ~100 up to 140 GB.

We backup each virtual machine every day and also backup the database seperatly on an iSCSI-Device. These are huge amounts of data, every day 100 GB or more..

In the Sybase Wiki are only the following options...

Is it possible only to backup/save database-data with the changes from yesterday to "now"?

asked 23 Jul '14, 14:59

pmiller's gravatar image

accept rate: 37%

edited 23 Jul '14, 15:12

This article contains pointers to several other articles on the subject: Backup is easy, recovery is hard...

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answered 24 Jul '14, 09:38

Breck%20Carter's gravatar image

Breck Carter
accept rate: 20%

On day "one" take a full backup that will back up both the database file and the active transaction log, and rename and restart the transaction log.

dbbackup -c dba,sql -r -n d:\backup

d:\backup now contains pmiller.db and YYMMDD##.log (for example, 140723AA.log)

Each day, take an incremental backup, which will only backup the transaction log, not the database file, and again rename and restart the transaciton log. The transaciton log contain all the operations that took place since the last backup.

dbbackup -c dba,sql -t -r -n d:\backup

d:\backup now contains pmiller.db and another YYMMDD##.log (for example 140724AA.log)

If you ever need to recover, the database and log files in d:\backup can be used to recover the database.

At some point, on day "X" archive the contents of the d:\backup directory, and start over again by taking a full backup.

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answered 23 Jul '14, 15:53

Reg%20Domaratzki's gravatar image

Reg Domaratzki
accept rate: 36%


See various links in*d5e63766 which talk about Backup and data recovery. In particular, you need to ensure you know and have tested your recovery plan to restore from backup. You should also make a copy of your backup and validate your backup (note you must not start the original backup copy of the database, otherwise you will be unable to apply the transaction logs to it and restore your database).

(24 Jul '14, 09:26) Ian McHardy
Replies hidden

Ian makes an excellent point that I should have mentionned instead of simply directly answering your question.

The best backup strategy in the world in 100% useless if you don't know how to recover from your backed up files. The best backup strategy in the world is 98% useless if you have never tested it. The best backup strategy in the world is 90% useless if you don't periodically test your recovery with the files you are backing up. All percentages given in this post are estimates, although they are acurrate to within 10%.

(24 Jul '14, 10:33) Reg Domaratzki

The best backup strategy in the world in 100% useless if you don't know how to recover from your backed up files.

Certainly true. However, I'd say there is a chance that you can still ask someone what to do and therefore may be able to recover successfully. At least that chance is bigger than when you have no backup at all, and the latter seems still appear now and then, even in questions on this forum...

Note: That remark is in no way meant as contradiction to Ian's and your warnings.

(24 Jul '14, 11:54) Volker Barth

Just to add to Reg's answer:

There are two different kinds of "incremental backups" that are desribed in the SQL Anywhere documentation, i.e. you make a full backup and then

  • just backup the transaction log and rename it (or truncate it) - which leads to a series of several log backups until the next full backup, as Reg has explained, or

  • just backup the transaction log without renaming/truncating it - which leads to only one (and therefore "growing") log backup until the next full backup - that's what some folks call a "differential backup", however the official docs do not use that name AFAIK.

The latter has the advantage that you do not have to apply a series of logs in case of recovery but only one file.

Apparently, it has the drawback that the current log itself will be bigger between full backups, and it will take longer to do the log backup itself.

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answered 24 Jul '14, 07:18

Volker%20Barth's gravatar image

Volker Barth
accept rate: 34%

edited 24 Jul '14, 07:29

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question asked: 23 Jul '14, 14:59

question was seen: 1,812 times

last updated: 24 Jul '14, 11:56