From 4ffd6f37b25fcbeb0a637c86c278feea5c6b8bc1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Antoine=20Beaupr=C3=A9?= <anarcat@debian.org>
Date: Thu, 25 Mar 2021 11:52:15 -0400
Subject: [PATCH] another benchmark, more positive
---
howto/new-machine-cymru.md | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/howto/new-machine-cymru.md b/howto/new-machine-cymru.md
index fadb8c187..00f64ac28 100644
--- a/howto/new-machine-cymru.md
+++ b/howto/new-machine-cymru.md
@@ -1454,7 +1454,8 @@ general, you should expect:
* iSCSI (network, large) disks:
* read: IOPS=26.9k, BW=105MiB/s (110MB/s) (gigabit network
saturation, probably cached by the SAN)
- * write: IOPS=264, BW=1059KiB/s (1085kB/s)
+ * random write: IOPS=264, BW=1059KiB/s (1085kB/s)
+ * sequential write: 11MB/s (dd)
In other words, local disks can't quite saturate network (far from it:
they don't even saturate a 100mbps link). Network disks seem to be
@@ -1624,6 +1625,17 @@ load on the gnt-fsn cluster.
sdj: ios=8678/8580, merge=0/0, ticks=6036/516604, in_queue=522552, util=99.77%
sdh: ios=0/0, merge=0/0, ticks=0/0, in_queue=0, util=0.00%
+### Raw DD test, iSCSI disks, chi-node-04
+
+`dd` fares much better, possibly because we're doing sequential writing:
+
+ root@chi-node-04:/var/log/ganeti/os# dd if=/dev/zero of=/dev/disk/by-id/dm-name-tb-builder-03-root status=progress
+ 10735108608 bytes (11 GB, 10 GiB) copied, 911 s, 11.8 MB/s
+ dd: writing to '/dev/disk/by-id/dm-name-tb-builder-03-root': No space left on device
+ 20971521+0 records in
+ 20971520+0 records out
+ 10737418240 bytes (11 GB, 10 GiB) copied, 914.376 s, 11.7 MB/s
+
### Comparison, NVMe disks, fsn-node-07
root@fsn-node-07:~# fio --name=stressant --group_reporting <(sed /^filename=/d /usr/share/doc/fio/examples/basic-verify.fio; echo size=100m) --runtime=1m --filename=test --size=100m
--
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