I am not an expert in these subjects. I am just learning. :-)

But that's just what I understood. They recommend to disable disk write cache when installing SQL Server because of the potential risk of data loss and they also talk about enhanced caching controller systems which provide cache with less risk.

In my opinion it´s not easy to say if cache is good or bad. If you don´t have an "enhanced caching controller", then what is better? To enable or to disable disk cache?

Cache is very good for performance. But may be bad if "something" happens and there is data loss. It depends on the probability of this "something" to happen.

I've been using Firebird for many years in many servers with disk cache enabled and I don´t remember having problems.

I was just wondering if the difference in performance with disk cache enabled or disabled is similar in others RDBMS.

 

Eduardo,

Did you read this?
"Enhanced caching controller systems disable on-disk cache and provide a functional battery-backed caching solution."

The idea of this article that battery-backed cache solutions should be used, instead of drives with simple cache.
It does not tell that cache is bad, just highlights the potential risk of data loss if caching without BBU is used.

So, essentially you need to buy advanced disk controller and properly setup it - that's true.

Regards,
Alexey Kovyazin
IBSurgeon

 

 

There is an interesting (and quite long) article about SQL Server and disk cache in MS site.

https://support.microsoft.com/en-us/kb/234656

They talk about "enhanced caching controllers" and they say things like the following:

• - SQL Server installations are targeted at systems that provide caching controllers. These controllers disable the on-disk caches and provide stable media caches to satisfy SQL Server I/O requirements.
• - Your SQL Server installation depends on the controller's ability to disable the on-disk cache and to provide a stable I/O cache.
• - Note: If you have any question about the caching status of your disk drive, contact the manufacturer and obtain the appropriate utility or jumper settings to disable write caching operations.

You even can see a list of different HD drive types (IDE, ATA, SATA, SCSI) with instructions to disable disk cache. In any of them you will see the following phrase:

• - Disk caching should be disabled in order to use the drive with SQL Server.

-------- Mensaje original --------
Asunto: Re: [firebird-support] Bad performance of Firebird in Windows Server 2012
De: Alexey Kovyazin ak@... [firebird-support] <firebird-support@yahoogroups.com>
Para: firebird-support@yahoogroups.com
Fecha: 31/12/2015 15:22

 

Hi Eduardo,

Can you please give links to these articles?

Regards,
Alexey Kovyazin
IBSurgeon

I searched in Google and found that, for instance, MS suggests not to install SQL Server in a domain controller, but for security reasons. In some articles, MS even recommends to disable disk write cache when installing SQL Server.

I searched information about others RDBMS and generally they recommend to disable disk write cache to ensure database integrity. This seems reasonably. That´s why I am surprised about the difference in performance.

Regards

Eduardo

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