Forgive me for asking but it seems most OS's require a swap file and when I 
look into doing something similar(meaning not having anything), they all say 
the OS could go unstable without it.  It seems that anyone doing this needs to 
be 100 certain memory will not be used at 100% ever or the OS would crash if no 
swap was there.  How are you getting around this and has it ever been a thing?

Also, for the ceph OSDs, where are you storing the osd and host configurations 
( central storage? )?

Regards,
-Brent

Existing Clusters:
Test: Nautilus 14.2.2 with 3 osd servers, 1 mon/man, 1 gateway, 2 iscsi 
gateways ( all virtual on nvme )
US Production(HDD): Nautilus 14.2.2 with 11 osd servers, 3 mons, 4 gateways, 2 
iscsi gateways
UK Production(HDD): Nautilus 14.2.2 with 12 osd servers, 3 mons, 4 gateways
US Production(SSD): Nautilus 14.2.2 with 6 osd servers, 3 mons, 3 gateways, 2 
iscsi gateways




-----Original Message-----
From: Martin Verges <[email protected]> 
Sent: Sunday, March 22, 2020 3:50 PM
To: [email protected]
Cc: ceph-users <[email protected]>
Subject: [ceph-users] Re: Questions on Ceph cluster without OS disks

Hello Samuel,

we from croit.io don't use NFS to boot up Servers. We copy the OS directly into 
the RAM (approximately 0.5-1GB). Think of it like a container, you start it and 
throw it away when you no longer need it.
This way we can save the slots of OS harddisks to add more storage per node and 
reduce overall costs as 1GB ram is cheaper then an OS disk and consumes less 
power.

If our management node is down, nothing will happen to the cluster. No impact, 
no downtime. However, you do need the mgmt node to boot up the cluster. So 
after a very rare total power outage, your first system would be the mgmt node 
and then the cluster itself. But again, if you configure your systems correct, 
no manual work is required to recover from that. For everything else, it is 
possible (but definitely not needed) to deploy our mgmt node in active/passive 
HA.

We have multiple hundred installations worldwide in production environments. 
Our strong PXE knowledge comes from more than 20 years of datacenter hosting 
experience and it never ever failed us in the last >10 years.

The main benefits out of that:
 - Immutable OS freshly booted: Every host has exactly the same version, same 
library, kernel, Ceph versions,...
 - OS is heavily tested by us: Every croit deployment has exactly the same 
image. We can find errors much faster and hit much fewer errors.
 - Easy Update: Updating OS, Ceph or anything else is just a node reboot.
No cluster downtime, No service Impact, full automatic handling by our mgmt 
Software.
 - No need to install OS: No maintenance costs, no labor required, no other OS 
management required.
 - Centralized Logs/Stats: As it is booted in memory, all logs and statistics 
are collected on a central place for easy access.
 - Easy to scale: It doesn't matter if you boot 3 oder 300 nodes, all boot the 
exact same image in a few seconds.
 .. lots more

Please do not hesitate to contact us directly. We always try to offer an 
excellent service and are strongly customer oriented.

--
Martin Verges
Managing director

Mobile: +49 174 9335695
E-Mail: [email protected]
Chat: https://t.me/MartinVerges

croit GmbH, Freseniusstr. 31h, 81247 Munich
CEO: Martin Verges - VAT-ID: DE310638492 Com. register: Amtsgericht Munich HRB 
231263

Web: https://croit.io
YouTube: https://goo.gl/PGE1Bx


Am Sa., 21. März 2020 um 13:53 Uhr schrieb [email protected] <
[email protected]>:

> Hello, Martin,
>
> I notice that Croit advocate the use of ceph cluster without OS disks, 
> but with PXE boot.
>
> Do you use a NFS server to serve the root file system for each node? 
> such as hosting configuration files, user and password, log files, 
> etc. My question is, will the NFS server be a single point of failure? 
> If the NFS server goes down, the network experience any outage, ceph 
> nodes may not be able to write to the local file systems, possibly leading to 
> service outage.
>
> How do you deal with the above potential issues in production? I am a 
> bit worried...
>
> best regards,
>
> samuel
>
>
>
>
> ------------------------------
> [email protected]
>
>
>
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