Migrating memcache to another host

Data in memcached have a big impact on database server. If you flush everything in the memcached and let the program fill the cached again, this might effect server performance for a while. To migrate memcached server there are memcached-tool and nc command to help you

$ memcached-tool server1:11211dump |nc server2 11211

This command will dump everything from server1 to server2. However, if your data didn't set expiration, the data might be lost during migration. As always, test what you are going to do before go to production.

memcached-tool

Memcached : memcached-tool display/manage memcached server information


memcached-tool  localhost -h
Usage: memcached-tool [mode]

       memcached-tool 10.0.0.5:11211 display    # shows slabs
       memcached-tool 10.0.0.5:11211            # same.  (default is display)
       memcached-tool 10.0.0.5:11211 stats      # shows general stats
       memcached-tool 10.0.0.5:11211 dump       # dumps keys and values
       memcached-tool 10.0.0.5:11211 move 7 9   # takes 1MB slab from class #7
                                                # to class #9.

You can only move slabs around on a server that supports 'slabs reassign'
messages and only once slab memory is totally allocated, and only
once the target class is full.  (So you can't move from #6 to #9 and #7
to #9 at the same itme, since you'd have to wait for #9 to fill from
the first reassigned page)