CentOS - May 2008 - OT: Building NFS server with LVM and snapshots enabled

Hi all,

  I need to build a NFS CentOS 5.1 based server with LVM and snaphosts for 
disaster recovering to serve storage to three ESX servers for a development 
dept. I have 500 GB for storage. Data that I need to store on this server is 150
GB and can grow to 210 GB to the end of year ...

  My questions are:

  - Is it possible to do some type of scripting to do data snapshots every day 
and then copy to a remote server?? Some example, please??

  - How can I restore snapshot data on the production server if I need to 
recover it??

  Openfiler or FreeNAS isn't an option to do this task (customer
requeriment).
-- 
CL Martinez
carlopmart {at} gmail {d0t} com

On Friday 16 May 2008 19:50:37 carlopmart wrote:
>   - Is it possible to do some type of scripting to do data snapshots every
> day and then copy to a remote server?? Some example, please??
>   - How can I restore snapshot data on the production server if I need to
> recover it??
>   Openfiler or FreeNAS isn't an option to do this task (customer
> requeriment).
This is a script to backup LVM using snapshot from Zimbra. Pls take a look at 
it and you can easily adjust it to your needs.
http://www.arinet.org/zimbra-backup-lvm.sh.txt
HTH,
-- 
Fajar Priyanto | Reg'd Linux User #327841 | Linux tutorial 
http://linux2.arinet.org
22:32:39 up 39 min, 2.6.22-14-generic GNU/Linux 
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carlopmart wrote:
> Hi all,
>
>  I need to build a NFS CentOS 5.1 based server with LVM and snaphosts 
> for disaster recovering to serve storage to three ESX servers for a 
> development dept. I have 500 GB for storage. Data that I need to store 
> on this server is 150 GB and can grow to 210 GB to the end of year ...
>
>  My questions are:
>
>  - Is it possible to do some type of scripting to do data snapshots 
> every day and then copy to a remote server?? Some example, please??
Yes of course. I would suggest to use rsync for that, see the example below.
I have experimented in the past with multiple snapshots a day over a 
week for users home space. The snapshots gave users a way to quickly 
retrieve lost data. Drawback is that snapshots tend to slow down the 
file server (it freezes temporarily to update the snaphot). A temporary 
snapshot during backup works OK.
>
>  - How can I restore snapshot data on the production server if I need 
> to recover it??
Most easy way would be to make a snapshot and make this snapshot the 
active disk. If you need to revert, just remove the snapshot and create 
a new one from the original unmodified data. But since you want to use 
NFS, you will have to reboot to free up the snapshot which is not so 
nice. The other way around is also possible. Just rsync the source NFS 
disk from the snapshot.
Again I would only make a snapshot temporarily and use it to make a copy 
(or sync) to a second file system. This second file system can than be 
setup with multiple snapshots over time. This prevents the slowdown of 
the "main" file server. If you need to revert you can use rsync again.
(rsync works incrementally so it safes a lot of time if most data is 
still the same)

Example script to run with crontab to synchronize multiple volumes to a 
backup server:

date +"$0 started: %x %T"
PATH=$PATH:/usr/sbin

volumes="vola volb volc vold"
for i in $volumes
do
  # Create a new snapshot
  # Maximum snapshot size 7G
  DATE=$(date +%a_%y%m%d_%H%M)
  lvcreate --size 10G -n ${i}_${DATE} --permission r --snapshot 
/dev/VolGroup00/$i

  # Mount the snapshot
  mkdir -p /snapshot/${DATE}/$i
  mount -o ro /dev/VolGroup00/${i}_${DATE}  /snapshot/${DATE}/$i

  rsync -aq --delete /snapshot/${DATE}/$i/ remote_host:/mnt/$i/

  umount /snapshot/${DATE}/$i
  rmdir  /snapshot/${DATE}/$i
  rmdir  /snapshot/${DATE}
  lvremove -f /dev/VolGroup00/${i}_${DATE}

done
date +"$0 finished: %x %T"


You could create daily snapshots on the remote server as well. I use 
(incremental) dump and restore for that.

Cheers,
Theo