[Ocfs2-users] ocfs2 vs ext3?

[Thomas G. Lau]

Dear Joel,

so how slow of OCFS2 actually?




_________
Thomas Lau
Product Engineer
Product Development
NTT Com Asia Limited
Phone: +852 3793-0733
Address: 12/F., Guardian House, 32 Oi Kwan Road, Wan Chai, Hong Kong
Email: thomas.lau at ntt.com.hk


Joel Becker wrote:
> On Wed, Apr 29, 2009 at 05:24:11PM +1000, Andrew (Anything) wrote:
>   
>>> 	I just checked max-features, it doesn't include "local" which means 
>>> that you still need to create dlm lock in your local node which will 
>>> cost some delay. You can check whether your volume enable "local" by 
>>> command
>>>
>>> echo 'stats'|debugfs.ocfs2 /dev/sdX|grep "Incompat"
>>>
>>> If the volume is mkfsed to used as local disk, you should see "local".
>>> Otherwise you need to add "--fs-features=local" to your mkfs.
>>>       
>
> 	Yeah, 'local' is a feature, but it's not a feature in any
> default list because we generally expect to be used in a cluster :-)
>
>   
>> Thanks for your replies Tao and Thomas
>>
>> I still intend on using the filesystem in a 3 node cluster, but when I found
>> it to be 25x slower than a single ext3 part I thought id start
>> troubleshooting at the start.
>>
>> I just did a format of a small partition to give it a quick test anyway, and
>> found that it performs just as well as ext3, in some test even better.
>>
>> Except if I understand correctly, local disables the ability for clustering
>> completely?
>>     
>
> 	There are a lot of safety concerns we have to make just in case
> there are other nodes in the cluster.  When in 'local' mode, those
> checks are all disabled, and that's why we can run as fast as any other
> local filesystem.  In a cluster mode, we have to have those checks
> enabled, and it does cause a speed penalty.  But remember, you're
> gaining the concurrent access on other nodes.  That's the tradeoff.  And
> I think we compare favorably in speed to other cluster filesystems.
>
> Joel
>
>   
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