rsync vs drbd

[Maaz]

I am planning a Replica site, I mean I want a clone of /home of an NFS server.

I have an NFS server(/home exported)

I have two options
1, RSYNC
2, DRBD

which of the above options is best in terms of
a, reliability
b, permormance/speed/fast
c, light weight

please suggest
Regards
Maaz

[likid0]

I have been using Rsync for a long time now, and never had a problem, so for reliability rsync works nicely

[Steven E. Protter · Accepted solution]

Shalom Maaz,

a) rsync is very reliable, and can send only changed files saving band with.
b) Due to rycnc sending only changed files this provides superior performance.
c) See past two answers.

rsync can use -e ssh to work through an encrypted ssh data stream, but that slows performance.

SEP

[Maaz]

Ok gurus thanks for the suggestions

the primary/actual NFS server is "serverA"
the backup/clone/secondary NFS server is "serverB"

If I go for rsync, I have two options

1
a, on the backup/secondary server(serverB) export /home via NFS
b, mount the /home of serverB on primary Server(ServerA) at /backup_home
c, create a cron job on primary server(ServerA)
*/2 * * * * rsync -av /home /backup_home

2
or the second option is that I configure the rsync server on primary server(serverA), then on secondary/backup server create a cron job
*/5 * * * * rsync -av serverA::home /home

which one is best
Regards
Maaz

[dirk dierickx]

you say you are planning a replica site, in that case drbd might not be the right choice since it works syncroniously, meaning that each write done on one site will be replicated immediatly and will only get a write confirm back when both servers have written the data.

depending on your link between the 2 sites this could cause problems.

rsync does nothing and waits for you to ask it to syncronise. problem is, if you wait to long site a & b might differ too much, you could lose the changes made since the last update.

i don't know if you have a SAN, but some SAN HW will allow replication on SAN level, perhaps you should look into that. benefits are it is platform independant.

[Maaz]

Dirk Dierickx
nice help/explanations dear Dirk Dierickx

>i don't know if you have a SAN
I am using Linux based iSCSI SAN

please also comment on my previous/last post in this thread

Thanks
Regards
Maaz

[Huc_1]

I would use rsync, mainly because that is what I use and now best, would investigate using iSCSI SAN tool is possible on your set up ?.

As for your options, I would go for option 2 because, well It seems simpler to me, you are only rsync every so often.. no fancy set up, keep-it simple.

I would wrap option 2 in a scrip so it send mail/or message on error.

enjoy life.

Jean-Pierre Huc

[Maaz]

Hi Jean-Pierre Huc

>I would go for option 2 because, well It seems
>simpler to me, you are only rsync every so
>often

you suggest the following
configure the rsync server on primary server(serverA), then on secondary/backup server create a cron job
*/5 * * * * rsync -av serverA::home /home

instead of

a, on the backup/secondary server(serverB) export /home via NFS
b, mount the /home of serverB on primary Server(ServerA) at /backup_home
c, create a cron job on primary server(ServerA)
*/2 * * * * rsync -av /home /backup_home

am I right ?

Regards

[Huc_1]

Yes, and mainly because I have always found solution that involving NFS to be more complicated, prone to time out and synchronization problems, less ease to debug.

I realize the above is just based on my own experience you may be more at ease then me as for as usage of NFS is concerned.

Enjoy life.

Jean-Pierre Huc

[Maaz]

Nice help FORUM ;)
Thanks and Regards
Maaz