Re: Questions about memcached in general and failover
a point... a query like select * from session_table where session_id='x' where session_id is a primary key is very very fast, we are talking about < 0.1 seconds, with memcached you are trying to go down to <0.01 seconds why should you care about speed in internet if the time to consider a page slow is near 3 seconds? you could use database without problems when memcached goes down and a simple query (in primary key) isn't database intensive, some guys use a mysql table per session when session ends DROP TABLE session_xyz this make the system more proof of broken engine (that don't work fast with frequently delete+update+select queries) other option is a session_table with many partitions, just some ideas.. 2012/10/22 Perrin Harkins : > On Mon, Oct 22, 2012 at 5:09 AM, SAE wrote: >> But as explained above. If one of the memcached servers goes down. Some >> users experience the problem, that they not only get logged out but also >> have problems browsing the site at all or logging back in. Every page needs >> minutes to load then and it seems like the client is still trying to reach >> the server that got down and he's not trying that for only the first few >> clicks after one server went down, but for every click after that. > > That sounds like an issue with your memcached client, rather than the > server. See if there's a mailing list or other support for the client > you're using. > > - Perrin -- Roberto Spadim
Re: Questions about memcached in general and failover
On Mon, Oct 22, 2012 at 5:09 AM, SAE wrote: > But as explained above. If one of the memcached servers goes down. Some > users experience the problem, that they not only get logged out but also > have problems browsing the site at all or logging back in. Every page needs > minutes to load then and it seems like the client is still trying to reach > the server that got down and he's not trying that for only the first few > clicks after one server went down, but for every click after that. That sounds like an issue with your memcached client, rather than the server. See if there's a mailing list or other support for the client you're using. - Perrin
Re: Questions about memcached in general and failover
First of all I want to thank all of you for your replys and I want to apologize, that I didn't replied earlier, but part of last week I was ill. However, I may have not put enough emphasis on my real problem. Some users losing their sessions is one thing that isn't that pretty, but not the end of the world. But as explained above. If one of the memcached servers goes down. Some users experience the problem, that they not only get logged out but also have problems browsing the site at all or logging back in. Every page needs minutes to load then and it seems like the client is still trying to reach the server that got down and he's not trying that for only the first few clicks after one server went down, but for every click after that.
Re: Questions about memcached in general and failover
there´s another solution, but i don't remember the name, redis could do the job (i think) 2012/10/16 Les Mikesell > On Tue, Oct 16, 2012 at 11:22 AM, Kiran Kumar wrote: > > > > Memcache doesn't automatically comes with Replication facility (High > > Avialibility) , i recomend you to use Repcache Patch on top of your > existing > > mecached for obtaining Replication of data > > within your servers . > > > > The only issue i see is that Repcached only works / Successfully Worked > when > > there are only two servers two replicate . > > If you are going to be stuck with this restriction - and have to build > your own fail-over, is there any advantage to using memcache compared > to redis with its much larger feature set? > > -- >Les Mikesell > lesmikes...@gmail.comi > -- Roberto Spadim
Re: Questions about memcached in general and failover
On Tue, Oct 16, 2012 at 12:59 PM, Les Mikesell wrote: > If you are going to be stuck with this restriction - and have to build > your own fail-over, is there any advantage to using memcache compared > to redis with its much larger feature set? I agree. If you need durability (i.e. if it would be a big problem to lose some of the data in memcached), then memcached is the wrong tool for you. It aims to provide a level of failover that allows memcached requests to continue to work, but does not aim to maintain data. - Perrin
Re: Questions about memcached in general and failover
On Tue, Oct 16, 2012 at 11:22 AM, Kiran Kumar wrote: > > Memcache doesn't automatically comes with Replication facility (High > Avialibility) , i recomend you to use Repcache Patch on top of your existing > mecached for obtaining Replication of data > within your servers . > > The only issue i see is that Repcached only works / Successfully Worked when > there are only two servers two replicate . If you are going to be stuck with this restriction - and have to build your own fail-over, is there any advantage to using memcache compared to redis with its much larger feature set? -- Les Mikesell lesmikes...@gmail.comi
Re: Questions about memcached in general and failover
garulf , Memcache doesn't automatically comes with Replication facility (High Avialibility) , i recomend you to use Repcache Patch on top of your existing mecached for obtaining Replication of data within your servers . The only issue i see is that Repcached only works / Successfully Worked when there are only two servers two replicate . On Tuesday, 16 October 2012 21:42:18 UTC+5:30, garulf wrote: > > > > 2012/10/16 SAE > > >> Hello, >> >> Hi > > >> We recently implemented memcached to keep our database from crashing >> because of too many connections to it. >> >> Now we have two memcached servers which handle the DB-access and as long >> as both servers are online we encounter no problems. However when one of >> the goes down. Half our users loose their sessions. >> > Can anyone help me to figure out what is going on here, please? >> > > Maybe you should read at this http://dormando.livejournal.com/495593.html > > >> >> Another thing is, that we would prefer to have the exact same data >> available on both memcached-Servers. So if one of the two can't be reached, >> the other one is asked. So no user is losing his session when one server >> suddenly goes down. >> > > Memcached has a different architecture... If you have same data on both > memcached server you have to do cache invalidation and data sync.. a > nightmare... > > M > >
Re: Questions about memcached in general and failover
2012/10/16 SAE > Hello, > > Hi > We recently implemented memcached to keep our database from crashing > because of too many connections to it. > > Now we have two memcached servers which handle the DB-access and as long > as both servers are online we encounter no problems. However when one of > the goes down. Half our users loose their sessions. > Can anyone help me to figure out what is going on here, please? > Maybe you should read at this http://dormando.livejournal.com/495593.html > > Another thing is, that we would prefer to have the exact same data > available on both memcached-Servers. So if one of the two can't be reached, > the other one is asked. So no user is losing his session when one server > suddenly goes down. > Memcached has a different architecture... If you have same data on both memcached server you have to do cache invalidation and data sync.. a nightmare... M
Questions about memcached in general and failover
Hello, We recently implemented memcached to keep our database from crashing because of too many connections to it. Now we have two memcached servers which handle the DB-access and as long as both servers are online we encounter no problems. However when one of the goes down. Half our users loose their sessions. While thats ugly it is actually not the biggest problem. Because if one server goes down users not only get kicked out, but they also struggle to use the site at all. It seems like the apache-client doesn't recognizes that one of the memcached servers went down and still tries to reach that server on every fracking request. The only thing that were changed on the memcached client were the implementation of "memcached.so" in php.ini and changing the [Session]-settings to "session.save_handler memcached" and "session.save_path = memc01, memc02". Can anyone help me to figure out what is going on here, please? Another thing is, that we would prefer to have the exact same data available on both memcached-Servers. So if one of the two can't be reached, the other one is asked. So no user is losing his session when one server suddenly goes down. I already searched a lot and it actually confused me quite a bit (memcache and memcached) and didn't bring up any results for me specially my first problem. Maybe I'm just terrible at googling or to stupid to find the solution. Oh, and please don't feel offended by my probably bad grammar and spelling, while I am listening a reading quite a lot english. I don't write or speak the language often. However, any kind of help is welcome. :) SAE
