SQL Anywhere v. 11.0.1. 2713 - not able to validate database...

[Former Member]

Hi all,

Yesterday we experienced at a customer , one table of our database did not validate anymore. We tried to unload the full database, thats how we found the 'bad' table.  We unloaded the rows from this table, dropped the table, recreated the table , uploaded our unloaded rows , and did a dbvalidate afterwards. Problem solved. But our customer wants to know how this happened ?

What has caused this ? And how to avoid this in future ? We didn't change our software , its been running on the same version and on the same server for months/years. I've done some reading  (assertion errors and so on...) but i can't explain to my customers , it could be a sofware cause , or a hardware cause , or ... Customers most of the time are not IT technical database skilled people.

Any way of explaining this to my client ?

Any way of tracing/finding out what the problem was based on the corrupt db ? I do have a copy.

TIA

John

[Former Member]

Its not always possible to find a root cause with all corruptions. A corruption can happen but go undetected for a long time and will only be detected when the page/row is read for the next time. This sounds like what happened in your customer's case.

The best defense against an assertion is a good backup procedure and a solid understanding of how to restore from it. This Wiki link has some detailed info about assertions and recovery that could help your customer get a better understanding.

Handling an Assertion Failure - SAP SQL Anywhere - SCN Wiki

Thanks

Mark

[former_member188493]

First, check the RAM on the suspect computer. It is the least likely cause, BUT the most dangerous because bad RAM can permanently damage disk data... all disk data flows through RAM in both directions.

Then, check the hard drive itself.

Depending on the hardware, it can be cheaper to just replace the RAM and replace the hard drive than spend hours agonizing over suspected problems. For example, a high quality 1TB SATA drive costs about eighty bucks.

It goes without saying that a regular machine backup is being taken, with verify. I am becoming a fan of Acronis True Image 2016... I think when they get the recovery kinks out it will be a best-of-breed utility.

[Former Member]

Hi John,

What was the error message of failing validation? Running validation on running production system isn't ideal since this can result false validation errors. Instead, you should backup the database and then validate the backup.