> On Mar 14, 2021, at 5:42 AM, Leon Fauster via CentOS <centos@centos.org> 
> wrote:
> 
> Am 14.03.21 um 07:13 schrieb Nicolas Kovacs:
>> 
>> Now here’s the problem: it took me three and a half days of intense work to
>> restore everything and get everything running again. Three and a half days of
>> downtime is quite a stretch.
> 
> What was the real problem? Why did you need days to restore
> from backups? Maybe the new solution is attached here?

I would second what Leon said. Even though my backup is different (bareos), 
still my estimate of full restore to different machine would be: installation 
of new system (about 30 min at most), then restore of everything from bareos 
backup, which will depend on total size of everything to restore, the 
bottleneck will be 1 Gbps network connection. And I do not think my FreeBSD 
boxes with dozens of jails are much simpler than Nicolas's front end machine. 
Restore from backup is just restore from backup.

But under some circumstances that can be even faster. I once had quite 
important machine died (system board). But I had different hardware running 
less critical stuff, which accepted the drives from failed machine plus RAID 
card from it, after boot the only thing was necessary to address was network 
configuration (due to different device names). (both boxes have 8 port sata/sas 
backplane, all filesystems of machines live on hardware RAID-6…)

As far as distributed file systems are concerned, they are nice (but with seph 
you will need to have all boxes with the same size of storage). However, it is 
more expensive. Cheaper guy - I - goes with hardware RAID, and spare machine 
(if necessary that is: in a manner of grabbing less important box’s hardware to 
stick drives from failed into it).

Virtualization: in our shop (we use FreeBSD jails), it provides more security 
and flexibility. As far as “disaster recovery” is concerned, using jails 
doesn’t affect it in any way. But often helps to avoid disasters created by 
sudden conflict between packages, as only inseparable components are run in the 
same jail, so actual server is a bunch of jails each running one or two 
services, which gives extra robustness. And if A depends on C and B depends on 
D, and if  C and D conflict with each other, that doesn’t matter when A lives 
in one jail, and B lives in another.

One example of flexibility I just had another week: I migrated the box with 
couple of dozens of jail (most of them are independent servers with different 
IPs, “virtualized” in the manner they run if jails on some machine). To move 
the whole everything to another machine will take long, noticeable downtime, 
but moving jails one at a time made downtime of each as short as mere reboot 
cause. (In general, any sort of virtualization gives you that).

I hope, this helps.

Valeri

> --
> Leon
> 
> 
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