Thanks for the info Scott. Can I setup a primary server called A that uses the Postgres installation on a nfs mounted filesystem and then A does a daily backup of database A and restores to database B on same filesystem.
Then I have server B acting as cold standby and if server A goes down, then B would make the backup DB active? In this case, both server A and B have the same NFS mount, but B is not always writing to the data. The target environment I am moving to is a RAID5 system with mirrored discs. I will be getting a VM on a physical server and the mirrored disks will store the database. I would like to setup a primary and secondary as cold standby. I am fairly new to PG so asking these questions. Please advise. Thank you. On Tue, Dec 1, 2015 at 11:26 AM, Scott Mead <sco...@openscg.com> wrote: > > > On Nov 30, 2015, at 12:54, anj patnaik <patn...@gmail.com> wrote: > > 1) directory listing: > > /opt/nfsDir/postgres/9.4/ > /bin > /data > /etc > /pgAdmin3 > .... > > > The data directory will cause you many problems. You will need one data > directory that is accessed by one AND ONLY one host for each node > connected. You can't run an instance on multiple machines pointing to the > same 'data' directory simultaneously. Data directories cannot be shared by > multiple instances simultaneously, that's an active/active shared disk > cluster and most databases don't support it or require massive overhead ( > network/licensing I.e. Oracle rac) to do that. > > You *can* re-use the other directories, it can be wrought with issues, > and you need to carefully think though upgrades, etc.... > > 2) The way I am using PG now is that I have specified the directory above > as the location to install it (from graphical installer). > > Now, it appears that postgres places files in other directories besides > the one specified in the installer. For instance, there are scripts in > /etc/init.d to start the service. > > So in answering my own question: it appears PG places files in other dirs > so when I am given a new VM/different physical server with the same NFS > mount I would either need to copy these files over or better yet un-install > the current PG and re-install from scratch. > > Thanks, > ap > > On Fri, Nov 27, 2015 at 8:30 PM, Adrian Klaver <adrian.kla...@aklaver.com> > wrote: > >> On 11/27/2015 01:17 PM, anj patnaik wrote: >> >>> Hello, >>> Yes, postgres is currently installed on a nfs mounted file system. So >>> when graphical installer runs, there is a form which asks location for >>> installation. I specified this path /opt/nfsDir/Postgres where nfsDir is >>> a nfs mount. So currently this is where PG 9.4 lives. >>> >> >> What is under /opt/nfsDir/Postgres? >> >> >>> My question is when I am given a brand new VM on a different physical >>> server, can I mount that same NFS FS and use the Postgres or do I need >>> to re-install PG on new VM? >>> >> >> How are you using Postgres now? Please be specific, more detail is better >> then less at this point. >> >> >>> I am not sure if PG writes to any other directories besides the one >>> where it is installed. >>> >> >> >> >>> On the issue of logging, I see a lot of log statements because client >>> apps do upserts and since I use Tcl I don't have a SQL proc, but rather >>> I let it exception and then do an update on the row. >>> >> >> You can Tcl in the database: >> >> http://www.postgresql.org/docs/9.4/interactive/pltcl.html >> >> That will not change things if you let the database throw an exception >> there also. >> >> >> >>> So, you can limit the size of an individual log, but there is no way to >>> tell PG to keep the log file short? >>> >>> if i choose FATAL, I'd lose some log, right? >>> >>> Thank you! >>> ap >>> >>> >> -- >> Adrian Klaver >> adrian.kla...@aklaver.com >> > >
