[CentOS] lvm 1 drive fails whole vol data lost

Sun Dec 26 16:04:50 UTC 2010
Kwan Lowe <kwan.lowe at gmail.com>

On Sat, Dec 25, 2010 at 2:23 PM, Ryan Wagoner <rswagoner at gmail.com> wrote:
>
> RAID 5 does provide speed increases for read operations. There are
> still some applications where RAID 5 has its benefits. For a smaller
> department file server 3-4 TB drives in RAID 5 works great. The money
> saved can be put towards backups, etc. Having said that I use RAID 10
> for most applications.

I've been thinking about the whole backup/redundancy approach to
maintaining my home network. Though it is a "home" network, I use it
to support  my work so though it's not business critical, it can't
tolerate much downtime.

Two approaches that I see:

1) Use some form of RAID or mirroring and a backup process to provide
recoverability.

2) Maintain a centralized configuration in order to quickly re-build a
downed system.

They  are not completely separate, but I've been trying to move my
recovery philosophy to the latter to minimize costs.

For example, I used to backup my DNS/LDAP server by creating a
snapshot of the Xen LVM partition. Recovery was simply a matter of
restoring the backup.

The problem with this approach was that the number of virtual machines
started to balloon and with it, the storage requirements.  Though the
images were only 10G to 20G, I had dozens of them.  Not to mention
that the virtualization hosts keep changing: VMWare Server stopped
being free; The upstream vendor moved to KVM instead of Xen.

The approach I'm taking now is to use a combination of
Kickstart/Anaconda and cfengine with the goal of removing all host
identity from a OS instance.

For my DNS server, for example, I use kickstart to build a standard
image with a cfengine client. On bootup, cfengine pulls in the bind
configuration and within a few minutes I have a duplicate of the old
server. This is also much more resilient to changes in the underlying
VM technology.

There are still some kinks to work out. For one, I haven't backed up
the cfengine server the same way. Supposedly it's just a matter of
making the server its own client, but right now I'm using an image
backup and rsync copies to another fileserver.

I'm also trying to integrate a Spacewalk server into the mix.  This
will allow me to rebuild a system with the exact same packages (right
now I just update to the latest). In a real production environment
this is critical as some applications may only be certified against
particular kernel/glibc/etc.  versions.