[SPAM] - Re:redundant-servers question - Email found in subject

Tue Jan 22 23:57:06 UTC 2008

Heartbeat + DRBD

     >-----Original Message-----
     >From: owner-tlug-lxSQFCZeNF4 at public.gmane.org [mailto:owner-tlug-lxSQFCZeNF4 at public.gmane.org] On Behalf Of
     >Lennart Sorensen
     >Sent: Tuesday, January 22, 2008 3:45 PM
     >To: tlug-lxSQFCZeNF4 at public.gmane.org
     >Subject: [SPAM] - Re: [TLUG]: redundant-servers question - Email
     >found in subject
     >
     >On Tue, Jan 22, 2008 at 03:34:36PM -0500, teddy mills wrote:
     >>
     >> I have servers I need to make redundant.
     >> Live PC and a backup PC, both exactly the same hardware.
     >> Servers are Gentoo with RAID1.
     >>
     >> If I have any problems with any of the live servers then I pull
     >the
     >> network plug, and drop that network cable into its exact-copy
     >backup server.
     >>
     >> I thought about using rsync, to keep the backup servers the same
     >as the
     >> live servers.
     >> The weak point is the rsync complexity. If I miss even one
     >important
     >> file for rsync, then it renders the whole solution almost
     >useless.
     >> (ie. with 1000% confidence, I should be able to remove the live
     >server
     >> at any time, and replace it with the backup.)
     >> As well, I would have to do a worst-case scenario
     >test..ie..replace a
     >> live server with the backup.
     >>
     >> I would much prefer to use mdadm's rebuilding feature and hot-
     >swapping
     >> drives. (once per 24 hours, or as needed)
     >>
     >> LIVE PC.
     >> RAID1 with hotswap 2 drives.DRIVE-A and DRIVE-B
     >>
     >> BACKUP PC with 1 hotswap drive DRIVE-C.
     >>
     >> Everyday, hotswap exchange DRIVE-B and DRIVE-C.
     >> fdisk /dev/DRIVE-B, and let mdadm rebuild it.
     >> Leave the working backup in the backup PC.
     >>
     >> Using this method, I am virtually guaranteed that the backup
     >servers are
     >> exactly the same as the live servers.
     >> Only problem with this solution, is that every day I am breaking
     >and
     >> rebuilding the raid.
     >> With no room for errors. A LOT more risky than just letting the
     >RAID1
     >> run alone.
     >
     >Well you do realize raid1 isn't limited to just 2 drives right?
     >
     >You could leave the 2 disks in the raid alone, and add a 3rd
mirror
     >(at
     >least as far as I know) that you are swapping.
     >
     >I think I would personally prefer to just make sure my rsync
works.
     >You
     >could do the rsync, then take the disk out of the backup server
and
     >connect it on the live server and do a diff between the drives to
     >see
     >that all the files are the same (of course if the live server is
     >doing
     >work a few files might still be changing).
     >
     >Replication is a very hard problem to solve.
     >
     >--
     >Len Sorensen
     >--
     >The Toronto Linux Users Group.      Meetings: http://gtalug.org/
     >TLUG requests: Linux topics, No HTML, wrap text below 80 columns
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