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Posted to user@zookeeper.apache.org by jmmec <jm...@gmail.com> on 2016/02/24 00:56:26 UTC

Standalone ZK Server (3.4.6): RAM disk gotchas?

Hello,

I'm running ZK version 3.4.6 where clients connect to a standalone ZK
server using the ZK C-Client.  For various reasons the ZK Server database
is being moved to a RAM disk and I was wondering if there are any gotchas
to consider.  I realize that none of this is an officially supported
configuration, so I definitely understand if this scenario is frowned
upon.  :)

Here are two gotchas that I'm aware of:

1. If the server machine crashes/recovers the RAM disk will empty; this is
OK as it will be repopulated.

2. Clients trying to connect to a recovered server will be rejected since
the Server zxid (0) will be older than the zxid of previously connected
Clients and the Server will reject those connections.  I think I'll be able
to somehow detect this & have the Clients initiate new connections to the
Server (i.e. I ran a quick test where I forced a disconnect/connect on a
previously connected Client and the Server accepted it).

Thank you for any additional thoughts or concerns.

Kind regards....

Justin