Re: slow read-performance inside the vm

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that depends.. with which block size do you get those numbers? Ceph is really good with block sizes > 256kb, 1M, 4M...
 
 

German Anders















 
--- Original message ---
Asunto: slow read-performance inside the vm
De: Patrik Plank <patrik@xxxxxxxx>
Para: ceph-users@xxxxxxxxxxxxxx <ceph-users@xxxxxxxxxxxxxx>
Fecha: Thursday, 08/01/2015 20:21


Hi,

first of all, I am a “ceph-beginner“ so i am sorry for the trivial questions :).

I have build a ceph three node cluster for virtualization.

 

Hardware:

 

Dell Poweredge 2900

8 x 300GB SAS 15k7 with Dell Perc 6/i in Raid 0

2 x 120GB SSD in Raid 1 with Fujitsu Raid Controller for Journal + OS

16GB RAM

2 x Intel Xeon E5410 2,3 Ghz

2 x Dual 1Gb Nic

 

Configuration

 

Ceph 0.90

2x Network bonding with 2 x 1 Gb Network (public + cluster Network) with mtu 9000

read_ahead_kb = 2048

/dev/sda1 on /var/lib/ceph/osd/ceph-0 type xfs (rw,noatime,attr2,inode64,noquota)

 

ceph.conf:

 

[global]

 

fsid = 1afaa484-1e18-4498-8fab-a31c0be230dd

mon_initial_members = ceph01

mon_host = 10.0.0.20,10.0.0.21,10.0.0.22

auth_cluster_required = cephx

auth_service_required = cephx

auth_client_required = cephx

filestore_xattr_use_omap = true

public_network = 10.0.0.0/24

cluster_network = 10.0.1.0/24

osd_pool_default_size = 3

osd_pool_default_min_size = 1

osd_pool_default_pg_num = 128

osd_pool_default_pgp_num = 128

filestore_flusher = false

 

[client]

rbd_cache = true

rbd_readahead_trigger_requests = 50

rbd_readahead_max_bytes = 4096

rbd_readahead_disable_after_bytes = 0



rados bench -p kvm 200 write –no-cleanup

 

Total time run: 201.139795

Total writes made: 3403

Write size: 4194304

Bandwidth (MB/sec): 67.674

Stddev Bandwidth: 66.7865

Max bandwidth (MB/sec): 212

Min bandwidth (MB/sec): 0

Average Latency: 0.945577

Stddev Latency: 1.65121

Max latency: 13.6154

Min latency: 0.085628

 

rados bench -p kvm 200 seq

 

Total time run: 63.755990

Total reads made: 3403

Read size: 4194304

Bandwidth (MB/sec): 213.502

Average Latency: 0.299648

Max latency: 1.00783

Min latency: 0.057656


So here my questions:

 

With these values above, I get a write performance of 90Mb/s and read performance of 29Mb/s, inside the VM. (Windows 2008/R2 with virtio driver and writeback-cache enabled)

Are these values normal with my configuration and hardware? -> The read-performance seems slow.

Would the read-performance better if I run for every single disk a osd?

 

Best regards

Patrik

 

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