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....@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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