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EXT4 Filesystem and "commit" Value

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joeN
New Member
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EXT4 Filesystem and "commit" Value

Hi,

 

Do we need to set "commit=1" for EXT4 filesystems (default value appears to be 5 secs)?

 

The DS 5.2 Admin, discusses updating the "commit" property in fstab.

 

I was thinking based on the guide to either update the EXT4 partition arguments (in /etc/fstab) with either:

 

 

auto_da_alloc,noatime

 

 

or
 
auto_da_alloc,noatime,commit=1

 

REFERENCE:

Ext4 Filesystem

 

commit=nrsec (*)
 
Ext4 can be told to sync all its data and metadata
every 'nrsec' seconds. The default value is 5 seconds.
This means that if you lose your power, you will lose
as much as the latest 5 seconds of work (your
filesystem will not be damaged though, thanks to the
journaling). This default value (or any low value)
will hurt performance, but it's good for data-safety.
Setting it to 0 will have the same effect as leaving
it at the default (5 seconds).
Setting it to very large values will improve
performance.

 

https://www.kernel.org/doc/Documentation/filesystems/ext4.txt

 

Cheers,

 

--Joe

 

1 REPLY
UnboundID KevinL
UnboundID
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Solution

Re: EXT4 Filesystem and "commit" Value

This is one of the areas where fast disk is King. Having a default of 5 seconds could mean 10's of thousands of changes being lost in some very heavy load scenarios.  It is easy for me to do >2000 modifies a second on some systems in fact in some cases we can do well over 20k changes a second.  So yes our recommendation is to have this value set to commit=1 for that reason.  Data reliability should always take precidence over performance.  If they need high performance then SSDs are the best option.