Regarding Consistent Hashing....
ajinkya at truesparrow.com
Thu Aug 30 06:03:53 UTC 2007
Basically, we are using Amazon's EC2 servers as memcached servers.
So as and when we see an increase in traffic/load, we expect to add more EC2
servers to the memcached cloud. And when the traffic/load subsides (lets say
after a week or so), we might remove a few servers from the cloud.
In such a scenario, if using normal hashing, I believe we would have to
flush everything when adding/removing memcached servers.
Do you think doing this might cause the system to go in a spin and might be
a risky proposition, and so we should rather consider using consistent
Or do you think this is not a big deal and we should rather use the regular
hashing (which is more stable)?
Please let me know your comments on this.
From: Mikael Johansson [mailto:mikael at synd.info]
Sent: Thursday, August 30, 2007 11:03 AM
To: Ajinkya Nahar
Cc: memcached at lists.danga.com; sunil at truesparrow.com; 'Nishith Shah'
Subject: Re: Regarding Consistent Hashing....
I believe there's already people using consistent hashing on large
installs out there. As to the pecl/memcache client the code is not
released and still in CVS, but it is stable (and certainly ready to be
evaluated/tested), also a release is coming up so you can either wait
for that or build from source like
cvs -d :pserver:cvsread at cvs.php.net:/repository checkout pecl/memcache
make && make install
Enable it by setting an php.ini entry like
memcache.hash_strategy = consistent
Please note that the consistent hashing implementation might still
change in the future when a standard is reached on the subject.
Ajinkya Nahar wrote:
> Hi all,
> I want to know whether consistent hashing technique can be used in
> production environment.
> Is it still too young or is it of production quality?
> Also, what configuration needs to be done in the PHP client when using
> consistent hashing?
> Please let me know.
> Thanks in advance.
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