Regarding Consistent Hashing....

[Ajinkya Nahar]

Hi,

 

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
hashing?

 

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.

 

Regards,

Ajinkya 

 

-----Original Message-----
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....

 

Hi,

 

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

 cd pecl/memcache

 phpize

 ./configure

 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.

 

//Mikael

 

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.

> 

> Regards,

> 

> Ajinkya

> 

>  

> 

 

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