Re: Rados performance inconsistencies, lower than expected performance

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I am on 4 nodes, mostly hdds, and 4x samsung sm863 480GB
2x E5-2660
2x LSI SAS2308 
1x dual port 10Gbit (one used, and shared between cluster/client vlans)

I have 5 pg's scrubbing, but I am not sure if there is any on the ssd 
pool. I am noticing a drop in the performance at the end of the test. 
Maybe some caching on the ssd?

rados bench -p rbd.ssd 60 write -b 4M -t 16
Bandwidth (MB/sec):     448.465
Average Latency(s):     0.142671

rados bench -p rbd.ssd 180 write -b 4M -t 16
Bandwidth (MB/sec):     381.998
Average Latency(s):     0.167524


-----Original Message-----
From: Menno Zonneveld [mailto:menno@xxxxxxxx] 
Sent: donderdag 6 september 2018 15:52
To: Marc Roos; ceph-users
Subject: RE:  Rados performance inconsistencies, lower than 
expected performance

ah yes, 3x replicated with minimal 2.


my ceph.conf is pretty bare, just in case it might be relevant

[global]
	 auth client required = cephx
	 auth cluster required = cephx
	 auth service required = cephx

	 cluster network = 172.25.42.0/24

	 fsid = f4971cca-e73c-46bc-bb05-4af61d419f6e

	 keyring = /etc/pve/priv/$cluster.$name.keyring

	 mon allow pool delete = true
	 mon osd allow primary affinity = true

	 osd journal size = 5120
	 osd pool default min size = 2
	 osd pool default size = 3


-----Original message-----
> From:Marc Roos <M.Roos@xxxxxxxxxxxxxxxxx>
> Sent: Thursday 6th September 2018 15:43
> To: ceph-users <ceph-users@xxxxxxxxxxxxxx>; Menno Zonneveld 
> <menno@xxxxxxxx>
> Subject: RE:  Rados performance inconsistencies, lower 
> than expected performance
> 
>  
> 
> Test pool is 3x replicated?
> 
> 
> -----Original Message-----
> From: Menno Zonneveld [mailto:menno@xxxxxxxx]
> Sent: donderdag 6 september 2018 15:29
> To: ceph-users@xxxxxxxxxxxxxx
> Subject:  Rados performance inconsistencies, lower than 
> expected performance
> 
> I've setup a CEPH cluster to test things before going into production 
> but I've run into some performance issues that I cannot resolve or 
> explain.
> 
> Hardware in use in each storage machine (x3)
> - dual 10Gbit Solarflare Communications SFC9020 (Linux bond, mtu 9000)
> - dual 10Gbit EdgeSwitch 16-Port XG
> - LSI Logic / Symbios Logic SAS2308 PCI-Express Fusion-MPT SAS-2 HBA
> - 3x Intel S4500 480GB SSD as OSD's
> - 2x SSD raid-1 boot/OS disks
> - 2x Intel(R) Xeon(R) CPU E5-2630
> - 128GB memory
> 
> Software wise I'm running CEPH 12.2.7-pve1 setup from Proxmox VE 5.2 
> on all nodes.
> 
> Running rados benchmark resulted in somewhat lower than expected 
> performance unless ceph enters the 'near-full' state. When the cluster 

> is mostly empty rados bench (180 write -b 4M -t 16) results in about 
> 330MB/s with 0.18ms latency but when hitting near-full state this goes 

> up to a more expected 550MB/s and 0.11ms latency.
> 
> iostat on the storage machines shows the disks are hardly utilized 
> unless the cluster hits near-full, CPU and network also aren't maxed 
> out. I’ve also tried with NIC bonding and just one switch, without 
> jumbo frames but nothing seem to matter in this case.
> 
> Is this expected behavior or what can I try to do to pinpoint the 
> bottleneck ?
> 
> The expected performance is per Proxmox's benchmark results they 
> released this year, they have 4 OSD's per server and hit almost 
> 800MB/s with 0.08ms latency using 10Gbit and 3 nodes, though they have 

> more OSD's and somewhat different hardware I understand I won't hit 
> the 800MB/s mark but the difference between empty and almost full 
> cluster makes no sense to me, I'd expect it to be the other way 
around.
> 
> Thanks,
> Menno
> _______________________________________________
> ceph-users mailing list
> ceph-users@xxxxxxxxxxxxxx
> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
> 
> 
> 


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