[CentOS] Bare metal vs. virtualization: Proxmox + Ceph + CentOS ?

Sun Mar 14 16:51:02 UTC 2021
Valeri Galtsev <galtsev at kicp.uchicago.edu>

> On Mar 14, 2021, at 5:42 AM, Leon Fauster via CentOS <centos at 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.


> --
> Leon
> _______________________________________________
> CentOS mailing list
> CentOS at centos.org
> https://lists.centos.org/mailman/listinfo/centos