[rabbitmq-discuss] RabbitMQ writes non stop to disk
matthias at rabbitmq.com
Thu Oct 27 02:29:55 BST 2011
On 27/10/11 01:47, Matthias Radestock wrote:
> Can you find out what files the 6k/s writes are going to? It can't be
> just the persistent message store since, as you observed, that's only
> writing 16M about every couple of minutes. And while I would expect to
> see some writes to the queue index journal files, these shouldn't add up
> to anywhere near 6k/s with the traffic levels you are reporting.
Btw, are you definitely looking at the correct column in the iostat output?
As a test I ran 'MulticastMain -f persistent -q 1 -r 17 -s 50000' (i.e.
17msg/s, persistent, qos=1, 50k message size), and the same with "-r 8"
- which roughly corresponds to the rates I saw reported on the two
queues in the system with non-negligible traffic. I adjusted rabbit's
memory thresholds s.t. the target_ram_count of the queues dropped to
zero but w/o raising the memory alarm. 'iostat -d -x 10' shows:
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s
avgrq-sz avgqu-sz await svctm %util
sda 0.00 219.70 0.00 57.70 0.00 2219.20
38.46 0.61 10.57 10.55 60.90
So that's just 57.70 writes/s.
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