high-availability again

zorg zorg at probesys.com
Fri Apr 15 04:48:15 EDT 2005

Hi c
ould you give me just some more explaination of what is the stage./ 
files used during LMTP delivery have unique filenames
so if i underdstand what you saying. if the stage./ files used during 
LMTP delivery is the same for all the node of the cluster share the same 
SAN then there won't be any problem


Ben Carter a écrit :

> Dave McMurtrie wrote:
>> Amos wrote:
>>> What sort of changes did you have to make?
>> We just had to change map_refresh() to call mmap() with MAP_PRIVATE 
>> instead of MAP_SHARED.  Since mmap() is being called with PROT_READ 
>> anyway, this doesn't affect the operation of the application since 
>> the mapped region can never be updated.  Veritas CFS was not very 
>> efficient about maintaining cache coherency across all cluster nodes 
>> when we were using MAP_SHARED.  Everything worked, but under heavy 
>> load it became extremely slow.
> Actually, the important code change for any active/active cluster 
> configuration is to make sure the stage./ files used during LMTP 
> delivery have unique filenames across the cluster.
> There are some other setup differences related to this same issue such 
> as symlinking /var/imap/proc, /var/imap/socket, and if you care 
> /var/imap/log to local filesystem space on each cluster node.  You 
> could make these filenames unique across the cluster with code changes 
> if you want to make the code changes for these also.
> We added a "clusternode" parameter to imapd.conf to accomplish this 
> for the LMTP stage./ files.
> Otherwise, it just worked.
> Ben

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