-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 08/24/07 08:21, Markus Schiltknecht wrote: > Hi, > > Matthew wrote: >> Hey all, new postgres user here. We are trying to setup/research an >> HA/Replicated solution with Postrgresql between a datacenter in LA and a >> d.c. in NY. >> >> We have a private LAN link between the two D.C.'s with a max round-trip >> of 150ms. >> >> We will have a web server at each d.c. (among other servers) that will >> write/read to/from the local LAN DB. On writes, that data should be >> xmited to the other data center so that if, for whatever reason, my >> website request was sent to LA instead of NY, all my session information >> etc will still exist. > > This is commonly known as synchronous replication. As that involves > *at-least* one round-trip *before* committing, it's quite expensive. Can > you live with a delay of ~150ms before COMMIT confirmation? Which puts an upper limit on transaction rates at 6TPS. Blech. > Another issue is the reliability of your failure detectors. How does > server B know that server A is really down (and not only the link?). > Normally, that's solved with a quorum device. So that you have to have > at least three servers - preferably in different locations. - -- Ron Johnson, Jr. Jefferson LA USA Give a man a fish, and he eats for a day. Hit him with a fish, and he goes away for good! -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQFGzu/7S9HxQb37XmcRArnEAJ947nvYFT1eQvRzj6YkpVEDLtLUqQCgsbQy rgyz2ZCrlGbS+RzzXTD1ybY= =SRQv -----END PGP SIGNATURE----- ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings
