Slower performance with ext4

[Fred Roller]

Chan Chung Hang Christopher wrote:
>>> You might want to also do a boot with your ext4 filesystems mounted with 
>>> 'barrier=0' in fstab.
>>>   
>>>     
>>>       
>> Can you explain what this does?
>>
>>
>>
>>   
>>     
>
>
> It disables write barriers. Write barriers are enabled by default on 
> ext4. Blast Mark, making me bone up on what is going on lately. :-)
>
> That means that if write-caches are enabled on disks, you are at risk of 
> losing data in the event of a sudden power loss but you get better 
> performance in return. Write barriers allow you to have write-caches 
> enabled and not have to risk losing data by ensuring that data is safely 
> on disk before saying "It's done."
>
> However, not everything disk related supports write-barriers, namely 
> device-mapper, so if you use LVM or any md module other than raid1, you 
> better turn write-caches off or get yourself a hardware raid card with 
> bbu cache or a bbu nvram card and data=journal.
>
>   
Steve and Chan, thank you.  Book marked the link for more in depth 
reading later.

-- 
Fred
www.fwrgallery.com

"Life is like linux, simple.  If you are fighting it you are doing something wrong."