Обсуждение: using warm standby with drbd???
Hi All!
I have configured the warm standby using WAL FILES and DRBD. The wal files are generated as server A. I am using DRBD to replicate these wal files between server A and server B. The DRBD service is running as Primary on Server A and secondary on Server B. The wal_files are written to the server B, but there is a drawback for DRBD. The filesystme needs to be unmounted on the server B (where DRBD is running secondary role).
So recovery is not countinuous.(file systme is unmounted). To start the recovery, i need to change the DRBD role to primary on server B. After that i have to mount the filesystem. Once i mount the filesystem, the recovery process starts.
Is there any way in which i need not switch secondary/primary role for DRBD on server B?
Is there any way in which i can have the file system mounted on server B, running DRBD secondary role?
How else can i replicate the wal_files? ( i don't want to user common file system ,,, NFS,,, etc.)?
Another thing which i want to ask is that if we are generating archives every 1 minute. then what happens to the data which was written to the server A after 35 seconds after the last wal file generation.(server A crashes).
Since this data has not been archived (it was supposed to archive after 1 minute), do i think that this is the loss of data in a server A crash as this 35 second data has not been written to the archived logs and neither has been transported to server B?
A quick reply is highly appreciated!
Thanks!
I have configured the warm standby using WAL FILES and DRBD. The wal files are generated as server A. I am using DRBD to replicate these wal files between server A and server B. The DRBD service is running as Primary on Server A and secondary on Server B. The wal_files are written to the server B, but there is a drawback for DRBD. The filesystme needs to be unmounted on the server B (where DRBD is running secondary role).
So recovery is not countinuous.(file systme is unmounted). To start the recovery, i need to change the DRBD role to primary on server B. After that i have to mount the filesystem. Once i mount the filesystem, the recovery process starts.
Is there any way in which i need not switch secondary/primary role for DRBD on server B?
Is there any way in which i can have the file system mounted on server B, running DRBD secondary role?
How else can i replicate the wal_files? ( i don't want to user common file system ,,, NFS,,, etc.)?
Another thing which i want to ask is that if we are generating archives every 1 minute. then what happens to the data which was written to the server A after 35 seconds after the last wal file generation.(server A crashes).
Since this data has not been archived (it was supposed to archive after 1 minute), do i think that this is the loss of data in a server A crash as this 35 second data has not been written to the archived logs and neither has been transported to server B?
A quick reply is highly appreciated!
Thanks!
On Tuesday 04 March 2008, "libra dba" <libra.dba@gmail.com> wrote: > How else can i replicate the wal_files? ( i don't want to user common > file system ,,, NFS,,, etc.)? scp > > Another thing which i want to ask is that if we are generating archives > every 1 minute. then what happens to the data which was written to the > server A after 35 seconds after the last wal file generation.(server A > crashes). > It's gone. If that isn't acceptable then I would suggest putting the active pg_xlog directory on drbd. That may have speed implications. -- Alan
On Mar 4, 2008, at 6:02 PM, Alan Hodgson wrote: > On Tuesday 04 March 2008, "libra dba" <libra.dba@gmail.com> wrote: >> How else can i replicate the wal_files? ( i don't want to user common >> file system ,,, NFS,,, etc.)? > > scp Actually, scp is a bad choice for transfering wal files if you're planning on continuous replay. You want something that supports atomic transfers. rsync is a typical choice and I've been meaning to check out unison for a while now. Erik Jones DBA | Emma® erik@myemma.com 800.595.4401 or 615.292.5888 615.292.0777 (fax) Emma helps organizations everywhere communicate & market in style. Visit us online at http://www.myemma.com