Slower performance with ext4
froller at tnclimited.com
Thu Nov 5 17:51:35 UTC 2009
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
"Life is like linux, simple. If you are fighting it you are doing something wrong."
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