From 8836bc547a526da32536783b4b183c7ab375fd3e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Antoine=20Beaupr=C3=A9?= <anarcat@debian.org>
Date: Tue, 4 Feb 2025 17:01:43 -0500
Subject: [PATCH] talk more about plain instances
---
howto/ganeti.md | 24 +++++++++++++++++++-----
1 file changed, 19 insertions(+), 5 deletions(-)
diff --git a/howto/ganeti.md b/howto/ganeti.md
index a429a1d0..8b51cc74 100644
--- a/howto/ganeti.md
+++ b/howto/ganeti.md
@@ -63,11 +63,7 @@ ram and 2 CPU cores:
This configures the following:
- * redundant disks in a DRBD mirror, use `-t plain` instead of `-t drbd` for
- tests as that avoids syncing of disks and will speed things up considerably
- (even with `--no-wait-for-sync` there are some operations that block on
- synced mirrors). Only one node should be provided as the argument for
- `--node` then.
+ * redundant disks in a DRBD mirror
* two additional partitions: one on the default VG (SSD), one on another
(HDD). A 512MB swapfile is created in `/swapfile`. TODO: configure disk 2
and 3 automatically in installer. (`/var` and `/srv`?)
@@ -126,6 +122,8 @@ Then follow [howto/new-machine](howto/new-machine).
### Other examples
+#### Dallas cluster
+
This is a typical server creation in the `gnt-dal` cluster:
gnt-instance add \
@@ -139,6 +137,10 @@ This is a typical server creation in the `gnt-dal` cluster:
--backend-parameters memory=8g,vcpus=2 \
test-01.torproject.org
+Do not forget to follow the [next steps](#next-steps), above.
+
+#### No DRBD, test machine
+
A simple test machine, with only 1G of disk, ram, and 1 CPU, without
DRBD, in the FSN cluster:
@@ -154,6 +156,18 @@ DRBD, in the FSN cluster:
Do not forget to follow the [next steps](#next-steps), above.
+Don't be afraid to create `plain` machines: they can be easily
+converted to `drbd` (with `gnt-instance modify -t drbd`) and the
+node's disk are already in RAID-1. What you lose is:
+
+ - High availability during node reboots
+ - Faster disaster recovery in case of a node failure
+
+What you gain is:
+
+ - Improved performance
+ - Less (2x!) disk usage
+
### iSCSI integration
To create a VM with iSCSI backing, a disk must first be created on the
--
GitLab