Re: high (or at least improved) availability and failover
От | Bruce Momjian |
---|---|
Тема | Re: high (or at least improved) availability and failover |
Дата | |
Msg-id | 200411270415.iAR4FUY28886@candle.pha.pa.us обсуждение исходный текст |
Ответ на | high (or at least improved) availability and failover ("Iain" <iain@mst.co.jp>) |
Список | pgsql-admin |
This thread been saved for the 8.1 release: http:/momjian.postgresql.org/cgi-bin/pgpatches2 --------------------------------------------------------------------------- Iain wrote: > HI, > > I've been looking into options for improving the availability of postgres > servers beyond what you get with a monolithic server and RAID. These are, as > far as possible "cheap" options and therefore don't include use of shared > storage and all the good options those systems have. > > Here is a very rough summary of my thoughts so far. I havn't actually tried > any of this yet, so if anyone has any thoughts, comments, additions I'd be > glad to hear from you. > > regards > iain > > Configurations for HA > ===================== > > Pgpool Only > ----------- > Pgpool can detect the failure of a server and failover automatically. > > Re-syncing the DBs after a failure will require the databases to be offline > for a file system copy. > > Should pgpool run on the db servers or a separate machine(s)? > > Performance impact of using the replication facility? Deadlock possibility? > > If the machine that pgpool is running on fails, need manual intervention to > start pgpool on another machine. > > Can only manage 2 servers at most. > > > Pgpool and Heartbeat > ----------------- > Similar to pgpool only, with the addition that pgpool itself can be failed > over automatically. > > > Heartbeat and DRDB > --------------- > Replication is done at the block level by DRDB. > > The database cannot be running on the standby server while it is being > replicated from the master. > > Automatic failover is possible as Heartbeat will start the database server > and switch to the standby if the master fails. > > A full re-sync of the DBs after a failure doesn't require the master to be > offline. > > Failure ofthe standby server typically doesn't require a full re-sync. > > Can't do load balancing. > > No particular need for pgpool as heartbeat will manage the aliased IP > address > > > Slony-I only > ------------ > Relies on triggers in the database, and some administration of the > replication configuration. > > Monitors replicated databases and performs automatic failover. > > When a failed server is brought back online it will automatically start > catching up with the other servers. > > When the master fails, clients can reconnect to the new master without > changing the IP address? > > > Slony-I and pgpool > --------------- > All the features of Slony-I > > Some load balancing of SELECT SQL is possible > > Need manual intervention if pgpool fails. > > > Slony-I and pgpool and Heartbeat > ---------------------------- > All the features of Slony-I with pgpool > > Use heartbeat to monitor the machines running pgpool and switch over > automatically if one fails. > -- Bruce Momjian | http://candle.pha.pa.us pgman@candle.pha.pa.us | (610) 359-1001 + If your life is a hard drive, | 13 Roberts Road + Christ can be your backup. | Newtown Square, Pennsylvania 19073
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