Bug 1394895

Summary: Slowness Writing to SAN Disk-backed Storage
Product: OpenShift Container Platform Reporter: Steven Walter <stwalter>
Component: StorageAssignee: Jeremy Eder <jeder>
Status: CLOSED NOTABUG QA Contact: Wenqi He <wehe>
Severity: urgent Docs Contact:
Priority: urgent    
Version: 3.2.0CC: aos-bugs, bchilds, ekuric, eparis, erich, hamiller, hchen, jeder, shberry
Target Milestone: ---Keywords: Performance
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard: aos-scalability-34
Fixed In Version: Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2017-01-27 16:17:10 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:

Description Steven Walter 2016-11-14 16:27:19 UTC
Description of problem:
Customer is seeing significant slowness when writing to disk. This appears to be occurring in OpenShift containers but NOT in vanilla docker containers.
The storage they are using is Gluster-based storage backed by SAN disks. The hosts are also backed by these SAN disks, so when using "ephemeral" storage (non-persistent volumes), it is using the same backing storage. Behavior is consistent regardless if the Gluster frontend is used, so it is not Gluster issue.

i/o tests for the SAN disk backend:

- Writing to the SAN disk from the VMWare host VM has good i/o speeds
- OpenShift pods with SAN disk-backed persistent volumes see very slow i/o writing to the storage
- Containers run with "docker run" see host-like i/o speeds

$ oc describe pvc esm-jenkins
Name:		esm-jenkins
Namespace:	esm
Status:		Bound
Volume:		app-pv-036-1g
Labels:		template=jenkins-persistent-template
Capacity:	1Gi
Access Modes:	RWO
No events.

$ oc describe pv app-pv-036-1g
Name:		app-pv-036-1g
Labels:		<none>
Status:		Bound
Claim:		esm/esm-jenkins
Reclaim Policy:	Recycle
Access Modes:	RWO
Capacity:	1Gi
Message:
Source:
    Type:		Glusterfs (a Glusterfs mount on the host that shares a pod's lifetime)
    EndpointsName:	glusterfs-cluster-app
    Path:		/app-pv-036-1G
    ReadOnly:		false
No events.



Version-Release number of selected component (if applicable):

3.2.0

How reproducible:
Not yet reproduced


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