Re: Problems when one of the memcached server down
On 3/8/2011 1:40 PM, Evil Boy 4 Life wrote: Thanks guys, I turned off the failover in the client... In fact, I didn't know that there are several .net clients and now I get confused, because I don't know which one is better (now I use memcacheddotnet) Do you know if one of the .net clients support replication in any way? Memcache isn't supposed to do replication - it's a cache that you should be able to replenish from the real data source. What happens when one server fails depends on the client hash mechanism. Some people want the load to be rebalanced evenly over the remaining servers, some don't. Either way, the next attempt to use a failed server should detect it is down and retrieve the data from the backing DB. -- Les Mikesell lesmikes...@gmail.com
Re: Problems when one of the memcached server down
it is, however, possible to support replication at the client level, if a bit out of band for memcached. we (Fotolog), for example, at one point wrote our own client that would set data in multiple servers and then get from only one of them. it was a read-heavy environment with a small dataset that easily fit completely into RAM on each server, so it actually worked. not saying that it is a good idea, just that as possible. anyway, it has since been replaced in our system with TokyoTyrant, which solved the problem much better for us... and it (or something similar) very well might in this case as well. awl On Mar 8, 2011 3:01 PM, Les Mikesell lesmikes...@gmail.com wrote: On 3/8/2011 1:40 PM, Evil Boy 4 Life wrote: Thanks guys, I turned off the failover in the client... In fact, I didn't know that there are several .net clients and now I get confused, because I don't know which one is better (now I use memcacheddotnet) Do you know if one of the .net clients support replication in any way? Memcache isn't supposed to do replication - it's a cache that you should be able to replenish from the real data source. What happens when one server fails depends on the client hash mechanism. Some people want the load to be rebalanced evenly over the remaining servers, some don't. Either way, the next attempt to use a failed server should detect it is down and retrieve the data from the backing DB. -- Les Mikesell lesmikes...@gmail.com
Re: Problems when one of the memcached server down
That client works, but it's a pretty bad java port and isn't maintained. You're probably better off using any of the other two clients: BeITMemcached or Enyim. I know my client doesn't support replication, and I don't think the Enyim one does either. And as other people have suggested, if you want replication, you should probably look at some other solution than memcached. /Henrik Schröder On Tue, Mar 8, 2011 at 20:40, Evil Boy 4 Life lior.m...@gmail.com wrote: Thanks guys, I turned off the failover in the client... In fact, I didn't know that there are several .net clients and now I get confused, because I don't know which one is better (now I use memcacheddotnet) Do you know if one of the .net clients support replication in any way? Thanks again!
Re: Problems when one of the memcached server down
I couldn't easily find any memcache .net documentation, but a user contributed note on the php memcache doc page says: http://php.net/manual/en/book.memcache.php The memcache changelog for 3.0.5 has the comment: Added method MemcachePool::findServer(key) which returns the server a key hashes to I bring this up because knowing (storing elsewhere) the server storing your key allows to handle the case when your key may no longer exist there and reload it from the database or file. Your client and or your server memcache/d versions may not provide these features. Also read the other thread `Replication ?`
Re: Problems when one of the memcached server down
Hi Lior, On 3/3/11 1:53 PM, Evil Boy 4 Life wrote: Hi, I use the .net clients and 2 servers at 2 different machines. When one of the memcached servers is down, I try to set an item to the cache (According the hashing algoritem of the client, this item should stored the inactive server!) and this item get stored at the active server. After I set the item, the second server get back to work. Now if I'll try to get this item I won't succeed, because the client will searche the item at the second server (According the hashing algoritem). Are you referring to the Enyim client? I believe there's a separate mailing list for that client, but I am not sure. What can i do to solve this problem??? (To set the item again at the second server isn't a solution, because I don't want to store any item at 2 servers) This seems like something more fundamental is wrong, or I miss the question. Keep in mind, having two servers isn't a situation where they are active/inactive, it's a collection of two servers. Each adds to the pool of cache available. It's normal for a given key to hash to one server or another, depending on the key. Are you saying that in a normal, no failures kind of situation, you cannot get and then set the same key? Matt
Re: Problems when one of the memcached server down
Which client are you using, there's at least three .Net clients? Either way, see if you can turn off failover in the client, that's what causing this behaviour. Alternatively, you can switch to my .Net client, which doesn't do failover at all: http://code.google.com/p/beitmemcached/ /Henrik On Thu, Mar 3, 2011 at 22:53, Evil Boy 4 Life lior.m...@gmail.com wrote: Hi, I use the .net clients and 2 servers at 2 different machines. When one of the memcached servers is down, I try to set an item to the cache (According the hashing algoritem of the client, this item should stored the inactive server!) and this item get stored at the active server. After I set the item, the second server get back to work. Now if I'll try to get this item I won't succeed, because the client will searche the item at the second server (According the hashing algoritem). What can i do to solve this problem??? (To set the item again at the second server isn't a solution, because I don't want to store any item at 2 servers)
Problems when one of the memcached server down
Hi, I use the .net clients and 2 servers at 2 different machines. When one of the memcached servers is down, I try to set an item to the cache (According the hashing algoritem of the client, this item should stored the inactive server!) and this item get stored at the active server. After I set the item, the second server get back to work. Now if I'll try to get this item I won't succeed, because the client will searche the item at the second server (According the hashing algoritem). What can i do to solve this problem??? (To set the item again at the second server isn't a solution, because I don't want to store any item at 2 servers)
