Parity Check Finished with Errors

[cherritaker]

I was hoping i could get some help on my parity check finishing with errors. I know for sure i had a unclean shutdown because one of my kids pushed open a hard drive caddy causing one disk to go missing not sure if that is the culprit i have attached a system log thank you.

tower-diagnostics-20180702-0659.zip

[JorgeB]

A few errors are expected after an unclean shutdown, as long as the next check results in 0 errors you're fine.

[cherritaker]

6 hours ago, johnnie.black said:

A few errors are expected after an unclean shutdown, as long as the next check results in 0 errors you're fine.

Its 521 errors to be exact not sure if that matters.

[JorgeB]

9 hours ago, cherritaker said:

Its 521 errors to be exact not sure if that matters.

That's a few errors and well withing the expected number after an unclean shutdown.

[FlorinB]

1 hour ago, johnnie.black said:

That's a few errors and well withing the expected number

Can you give us an interval for what means a few errors and what to do if there are more than a few?

 

Thank you.

[JorgeB]

5 minutes ago, FlorinB said:

Can you give us an interval for what means a few errors and what to do if there are more than a few?

Anything other than 0 sync errors is only acceptable in case of an unclean shutdown, if not there's a problem, as to the number of errors it can depend on what the server was doing when the shutdown happened, e.g., if it was writing there will be many more, but anything up to a few thousand sync errors if perfectly normal.

[FlorinB]

53 minutes ago, johnnie.black said:

in case of an unclean shutdown

Without an UPS, is there any possibility to find out after reboot if it was a power failure or not?

I understood that most of the things are running in memory, therefore are lost if an unexpected shutdown occurs.

[JorgeB]

12 minutes ago, FlorinB said:

is there any possibility to find out after reboot if it was a power failure or not?

When there's an unclean shutdown it's logged and an automatic parity check will start.

[FlorinB]

53 minutes ago, johnnie.black said:

When there's an unclean shutdown it's logged and an automatic parity check will start.

Thanks Johnnie. No more questions on this topic.

[cherritaker]

Thank's i ran another parity check and you where right what a relief came back with 0 errors.

[pwm]

On 7/3/2018 at 10:13 AM, FlorinB said:

Can you give us an interval for what means a few errors and what to do if there are more than a few?

 

Thank you.

 

It's hard to know what is a "good" number, because it depends on how much writes the machine was doing when it lost power. The more writes the machine does, the harder it is to have parity and the individual data disks to be perfectly in sync since there are no way to synchronize multi-disk writes. That's why enterprise-level RAID cards uses a cache with battery backup, to allow the OS to make a large array write and the RAID card then splits the large write into multiple smaller writes to the different disks of the array while still holding a copy in the nonvolatile cache until all disks have reported back an acknowledge.