Write Cache - Data Corruption

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Write Cache - Data Corruption

Shreyans Jain
If we have a ups and we properly shutdown the OS, will then we have to disable write cache for the hard-disk in order to prevent data corruption. Are there any chances left for the data to be corrupted by power failure with write cache on?

Regards,
Shreyans Jain
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Re: Write Cache - Data Corruption

Rick Hillegas-3
On 7/14/17 6:21 PM, Shreyans Jain wrote:
> If we have a ups and we properly shutdown the OS, will then we have to
> disable write cache for the hard-disk in order to prevent data
> corruption. Are there any chances left for the data to be corrupted by
> power failure with write cache on?
>
> Regards,
> Shreyans Jain

That will reduce your risk. But operating systems can crash before
flushing the cache to disk.

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Re: Write Cache - Data Corruption

Shreyans Jain
If we have write cache off, do we need a ups or some other power backup ?

On Sat, Jul 15, 2017 at 8:02 PM, Rick Hillegas <[hidden email]> wrote:
On 7/14/17 6:21 PM, Shreyans Jain wrote:
If we have a ups and we properly shutdown the OS, will then we have to disable write cache for the hard-disk in order to prevent data corruption. Are there any chances left for the data to be corrupted by power failure with write cache on?

Regards,
Shreyans Jain

That will reduce your risk. But operating systems can crash before flushing the cache to disk.


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Re: Write Cache - Data Corruption

Rick Hillegas-3
On 7/15/17 10:12 PM, Shreyans Jain wrote:
If we have write cache off, do we need a ups or some other power backup ?
I'm not an expert on ups's, but my understanding is that they provide other kinds of protective power conditioning which you would want in a production environment. See, for instance, https://en.wikipedia.org/wiki/Uninterruptible_power_supply.

Hope this helps,
-Rick

On Sat, Jul 15, 2017 at 8:02 PM, Rick Hillegas <[hidden email]> wrote:
On 7/14/17 6:21 PM, Shreyans Jain wrote:
If we have a ups and we properly shutdown the OS, will then we have to disable write cache for the hard-disk in order to prevent data corruption. Are there any chances left for the data to be corrupted by power failure with write cache on?

Regards,
Shreyans Jain

That will reduce your risk. But operating systems can crash before flushing the cache to disk.



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Re: Write Cache - Data Corruption

Shreyans Jain
Why would we need any kind of power backup if every thing is directly written to disk, write cache being off. Only risk would be of losing last transaction data.

On Jul 16, 2017 7:58 PM, "Rick Hillegas" <[hidden email]> wrote:
On 7/15/17 10:12 PM, Shreyans Jain wrote:
If we have write cache off, do we need a ups or some other power backup ?
I'm not an expert on ups's, but my understanding is that they provide other kinds of protective power conditioning which you would want in a production environment. See, for instance, https://en.wikipedia.org/wiki/Uninterruptible_power_supply.

Hope this helps,
-Rick

On Sat, Jul 15, 2017 at 8:02 PM, Rick Hillegas <[hidden email]> wrote:
On 7/14/17 6:21 PM, Shreyans Jain wrote:
If we have a ups and we properly shutdown the OS, will then we have to disable write cache for the hard-disk in order to prevent data corruption. Are there any chances left for the data to be corrupted by power failure with write cache on?

Regards,
Shreyans Jain

That will reduce your risk. But operating systems can crash before flushing the cache to disk.



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Re: Write Cache - Data Corruption

kristwaa

Correct, you absolutely don't need a UPS for Derby to function. The issues to consider with an abrupt shutdown would be loss of uncommitted transactions and recovery time.

There's also the usual additional risk that something goes awry in the OS or with the hardware itself. That risk is likely way lower than the risk of programming or operator error. In any case, this is when you want your backup and restore procedures to be tested and working.

As Rick pointed out, and which is described on the webpage referred to, a UPS can give you power of higher quality and protect your hardware.

Regards,
--
Kristian


Den søn. 16. jul. 2017, 16:42 skrev Shreyans Jain <[hidden email]>:
Why would we need any kind of power backup if every thing is directly written to disk, write cache being off. Only risk would be of losing last transaction data.

On Jul 16, 2017 7:58 PM, "Rick Hillegas" <[hidden email]> wrote:
On 7/15/17 10:12 PM, Shreyans Jain wrote:
If we have write cache off, do we need a ups or some other power backup ?
I'm not an expert on ups's, but my understanding is that they provide other kinds of protective power conditioning which you would want in a production environment. See, for instance, https://en.wikipedia.org/wiki/Uninterruptible_power_supply.

Hope this helps,
-Rick

On Sat, Jul 15, 2017 at 8:02 PM, Rick Hillegas <[hidden email]> wrote:
On 7/14/17 6:21 PM, Shreyans Jain wrote:
If we have a ups and we properly shutdown the OS, will then we have to disable write cache for the hard-disk in order to prevent data corruption. Are there any chances left for the data to be corrupted by power failure with write cache on?

Regards,
Shreyans Jain

That will reduce your risk. But operating systems can crash before flushing the cache to disk.



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