Move root to lvm after initial install (VPS)
Hi,
I'm currently moving my VPS to another provider. My current VPS is
limited to 1024 MB ram, and 50 GB of space. First I was leaning towards
just using a tar of the old system to install the new VPS. I actually
want this new system to be ready for high availability with drdb in the
future or another mechanism.
The machine I got is a 32 GB dedicated server Intel Xeon W3520 with 2x2TB
sata disks. I want to figure out HA before I even think of offer some
kind of service to customers. As I'm a start up I don't have the
resources to spend a lot of money on spare servers but I also don't want
to deal with crashing sites or servers when I'm not behind a desk.
Currently my VPS server has DNS, email and webserver. In the future, I
will use separate servers for this, but for now my plan is to setup this
2nd server first to move the services from my old vps to this one, and
use the old VPS for backup mx, and slave dns. For my website, I haven't
yet figured out a good way for automatic fail over (pretty new to this)
besides using a drdb partition and put the site, and the data (Postgres
db) on there.
In the web interface of the VPS provider (soyoustart) I was able to
specify raid partitions, for boot and swap. Choices for the partitions
where primary, logical and lv. However, when I tried to put root on lv,
it refused. The web interface isn't very handy and it would be more
convenient if I could use the debian installer.
Instead of having a raid partition with lvm for /, /usr, /var, /tmp, I
end up with this:
sda 8:0 0 1,8T 0 disk
├─sda1 8:1 0 1004,5K 0 part
├─sda2 8:2 0 511M 0 part
│ └─md2 9:2 0 511M 0 raid1 /boot
├─sda3 8:3 0 17,6G 0 part [SWAP]
├─sda4 8:4 0 30G 0 part
│ └─md4 9:4 0 30G 0 raid1 /
└─sda5 8:5 0 1,8T 0 part
└─md5 9:5 0 1,8T 0 raid1
├─vg-usr (dm-0) 254:0 0 20G 0 lvm /usr
├─vg-var (dm-1) 254:1 0 30G 0 lvm /var
└─vg-tmp (dm-2) 254:2 0 5G 0 lvm /tmp
Below is what I have on my local test system, and what seems like
something useful. I would use this layout for my new VPS (increased sizes
of course) and leave the rest of the space for a drdb partition or
whatever solution I end up with for failover.
sda 8:0 0 10G 0 disk
├─sda1 8:1 0 487M 0 part
│ └─md0 9:0 0 486,7M 0 raid1 /boot
├─sda2 8:2 0 954M 0 part
│ └─md1 9:1 0 953,4M 0 raid1 [SWAP]
└─sda3 8:3 0 8,6G 0 part
└─md2 9:2 0 8,6G 0 raid1
├─vg0-vg_root (dm-0) 253:0 0 2,8G 0 lvm /
├─vg0-lv_usr (dm-1) 253:1 0 2,8G 0 lvm /usr
├─vg0-lv_var (dm-2) 253:2 0 2,6G 0 lvm /var
└─vg0-lv_tmp (dm-3) 253:3 0 396M 0 lvm /tmp
Some questions:
- Is there a way to still get / on lvm on raid even if the web installer
doesn't seem to like it?
- Any easy way to get fail over for my site? I do have a small database
coupled to it. rsync seems possible but I doesn't seem safe to copy a
running db with it. And it still leaves me needing a mechanism to detect
when my site/server is down.
- Seems like I'll need 2 load balancers and 2 servers to really be safe
in the future. I think I would need at least 1 extra IP for the load
balancers, and use that IP adres in my DNS settings for my site/email
server. This way, the load balancers (HA Proxy, ...) get the requests,
and can forward the request to the right server. Is this correct?
- I've thought about kvm or linux containers to seperate the services on
the VPS. Not sure if these could be handy in my case. If I use containers
of some sort, I also need to get the data replicated to another server.
My old VPS is rather slow, and only has 50GB of space so my options are
limited. If I offer services, I will get another VPS similar to this new
VPS.
- If I would implement HA in the future, is a backup mx still useful?
I think it is. If so, that would mean having another server with just the
backup mx?
Thanks for any info,
Regards
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