Re: Behavior of Memcached Client during Replication Process
guy, why you don't study the source code? you sent a lot of messages with the same querstion! i will add your contact to spam with more messages like that read the wiki, read the source, understand the app, and stop asking the same message 100 times 2012/10/17 Kiran Kumar krn1...@gmail.com Hi , We are using Memcache in a different/wrong way , that is Memcache as a Complete Data Store itself . The setup of our Application is in such a way that , there are two Memcache servers (Server1 and Server2 )where both of them acting as active active (Master - Master ) each of them gets unique store of Data , and finally repcached is applied on top of these severs for providing replication . The Data is being replicated bethween these two servers and i observed that there is a small delay regarding the two servers being in sync with each other I am using Xmemcached 1.4 version as Memcache Client . I have these two questions with respect to the above set up of our Application . 1*. Is the XMemcached Client Smart enough to read Key from Server2 , incase it can't find that key in Sever 1 ( As i mentioned that there is a small delay till both the servers are in synch with each other )* 2. * Incase i configure my Memcache client to use KetamaMemcachedSessionLocator inside the code , will this be of any help with respect to the above scenario ??* Thank you very much . -- Roberto Spadim
Re: Behavior of Memcached Client during Replication Process
No, you will have to configure two client instances and read the key from both servers in your application. However, sometimes you will get a cache miss from one server and a cache hit from the other server. And you have no way of knowing if that happened because a value was written to one server, but the write didn't replicate yet, or if it was deleted from one server, and the delete didn't replicate yet. I'm still incredibly curious as to why your system writes data to both servers, you don't gain any performance whatsoever, you only create consistency problems for yourself, and you lock yourself into a setup where you can't utilize the linear scalability of memcached. /Henrik On Wed, Oct 17, 2012 at 6:24 PM, Kiran Kumar krn1...@gmail.com wrote: Hi , We are using Memcache in a different/wrong way , that is Memcache as a Complete Data Store itself . The setup of our Application is in such a way that , there are two Memcache servers (Server1 and Server2 )where both of them acting as active active (Master - Master ) each of them gets unique store of Data , and finally repcached is applied on top of these severs for providing replication . The Data is being replicated bethween these two servers and i observed that there is a small delay regarding the two servers being in sync with each other I am using Xmemcached 1.4 version as Memcache Client . I have these two questions with respect to the above set up of our Application . 1*. Is the XMemcached Client Smart enough to read Key from Server2 , incase it can't find that key in Sever 1 ( As i mentioned that there is a small delay till both the servers are in synch with each other )* 2. * Incase i configure my Memcache client to use KetamaMemcachedSessionLocator inside the code , will this be of any help with respect to the above scenario ??* Thank you very much .
Behavior of Memcached Client during Replication Process
Hi , We are using Memcache in a different/wrong way , that is Memcache as a Complete Data Store itself . The setup of our Application is in such a way that , there are two Memcache servers (Server1 and Server2 )where both of them acting as active active (Master - Master ) each of them gets unique store of Data , and finally repcached is applied on top of these severs for providing replication . The Data is being replicated bethween these two servers and i observed that there is a small delay regarding the two servers being in sync with each other I am using Xmemcached 1.4 version as Memcache Client . I have these two questions with respect to the above set up of our Application . 1*. Is the XMemcached Client Smart enough to read Key from Server2 , incase it can't find that key in Sever 1 ( As i mentioned that there is a small delay till both the servers are in synch with each other )* 2. * Incase i configure my Memcache client to use KetamaMemcachedSessionLocator inside the code , will this be of any help with respect to the above scenario ??* Thank you very much .
Re: Behavior of Memcached Client during Replication Process
On Wed, Oct 17, 2012 at 11:24 AM, Kiran Kumar krn1...@gmail.com wrote: Hi , We are using Memcache in a different/wrong way , that is Memcache as a Complete Data Store itself . The setup of our Application is in such a way that , there are two Memcache servers (Server1 and Server2 )where both of them acting as active active (Master - Master ) each of them gets unique store of Data , and finally repcached is applied on top of these severs for providing replication . The Data is being replicated bethween these two servers and i observed that there is a small delay regarding the two servers being in sync with each other I am using Xmemcached 1.4 version as Memcache Client . I have these two questions with respect to the above set up of our Application . 1. Is the XMemcached Client Smart enough to read Key from Server2 , incase it can't find that key in Sever 1 ( As i mentioned that there is a small delay till both the servers are in synch with each other ) 2. Incase i configure my Memcache client to use KetamaMemcachedSessionLocator inside the code , will this be of any help with respect to the above scenario ?? There should be options for how the client handles a server failure: http://code.google.com/p/xmemcached/wiki/FailureMode_StandbyNode Failure doesn't mean 'key doesn't exist', though, it means 'server connection fails'. -- Les Mikesell lesmikes...@gmail.com
Re: Behavior of Memcached Client during Replication Process
Les Mikesell , Thanks for the link , but unfortunately that is no where related to my question above . anyway once again , What i was asking is that as there is some delay in Data Replication , will the Memcache Client checks server2 also in case if it doesn't found in Server 1 . And does adding *KetamaMemcachedSessionLocator * to the code will help in anyway ?? On Wednesday, 17 October 2012 23:57:19 UTC+5:30, LesMikesell wrote: On Wed, Oct 17, 2012 at 11:24 AM, Kiran Kumar krn...@gmail.comjavascript: wrote: Hi , We are using Memcache in a different/wrong way , that is Memcache as a Complete Data Store itself . The setup of our Application is in such a way that , there are two Memcache servers (Server1 and Server2 )where both of them acting as active active (Master - Master ) each of them gets unique store of Data , and finally repcached is applied on top of these severs for providing replication . The Data is being replicated bethween these two servers and i observed that there is a small delay regarding the two servers being in sync with each other I am using Xmemcached 1.4 version as Memcache Client . I have these two questions with respect to the above set up of our Application . 1. Is the XMemcached Client Smart enough to read Key from Server2 , incase it can't find that key in Sever 1 ( As i mentioned that there is a small delay till both the servers are in synch with each other ) 2. Incase i configure my Memcache client to use KetamaMemcachedSessionLocator inside the code , will this be of any help with respect to the above scenario ?? There should be options for how the client handles a server failure: http://code.google.com/p/xmemcached/wiki/FailureMode_StandbyNode Failure doesn't mean 'key doesn't exist', though, it means 'server connection fails'. -- Les Mikesell lesmi...@gmail.com javascript:
Re: Behavior of Memcached Client during Replication Process
On Wed, Oct 17, 2012 at 1:56 PM, Kiran Kumar krn1...@gmail.com wrote: Les Mikesell , Thanks for the link , but unfortunately that is no where related to my question above . anyway once again , What i was asking is that as there is some delay in Data Replication , will the Memcache Client checks server2 also in case if it doesn't found in Server 1 . No, I can't imagine any circumstance where a memcache client would consider a key that doesn't exist in its expected location to be a server error. Why should it?I think the only way you can get that effect is to define only one server. All clients using the same hashing should store/retrieve it on the same target as the first choice anyway with the only reason to retry being if one is down - but that leaves you without a good way to handle the situation where the down instance is restarted and its cache is empty. -- Les Mikesell lesmikes...@gmail.com
