Bug 1497673

Summary: [GSS] Doc doesn't specify which volumes and what replica count is supported with RHV
Product: [Red Hat Storage] Red Hat Gluster Storage Reporter: Bipin Kunal <bkunal>
Component: doc-Configuring_Red_Hat_Enterprise_Virtualization_with_RHGSAssignee: Laura Bailey <lbailey>
Status: CLOSED CURRENTRELEASE QA Contact: SATHEESARAN <sasundar>
Severity: urgent Docs Contact:
Priority: urgent    
Version: rhgs-3.3CC: abhishku, apaladug, asriram, bkunal, kdhananj, lbailey, mpillai, nchilaka, sabose, sankarshan, sasundar, sheggodu, ssaha, vdas
Target Milestone: ---Keywords: ZStream
Target Release: RHGS 3.4.z Async Update   
Hardware: Unspecified   
OS: Unspecified   
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Fixed In Version: Doc Type: If docs needed, set a value
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Clone Of: Environment:
Last Closed: 2019-02-15 10:07:45 UTC Type: Bug
Regression: --- Mount Type: ---
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Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Bug Depends On:    
Bug Blocks: 1649191, 1660873    

Description Bipin Kunal 2017-10-02 12:25:05 UTC 
Description of problem: 

    AFAIK we support only replicate or distribute-replicate volume with replica 3 or arbiter with sharding. These things are not mentioned clearly in the doc.

    We should be precise and clear on what is supported and what is recommended.


This Bug has been opened to clarify and document few things :

    1) replicate or distribute-replicate volume(with and without sharding): Is this a supported volume or recommended volume. Is any other volume type supported for RHV? Only supported volume should be clearly indicated in the doc.
        As of now in the section :
             3.1. Using Red Hat Gluster Storage Volumes in the Red Hat Virtualization Manager 
         sub section: 7. Configure Storage
    """"
     For instructions on creating a Red Hat Gluster Storage Volume, see chapter 
     Red Hat Gluster Storage Volume in the Red Hat Gluster Storage 
     Administration Guide: https://access.redhat.com/documentation/en-
     us/red_hat_gluster_storage/3.3/html/administration_guide/chap-
     red_hat_storage_volumes.
    """"

   We directly point to a section in RHGS admin guide which discusses all types of volumes.

    2) Replica 3 or replica 3 with arbiter: Is this a support requirement or recommendation? 
       Current doc is a bit confusing and we do not have a strict guidance here.

      In Section 2.1. Prerequisites : 

       """
 
         To reduce the risk of split-brain conditions developing in the cluster, 
         Red Hat requires three-way replication when using Red Hat Gluster 
         Storage with Red Hat Virtualization. Three-way replication is provided 
         by three-way replicated volumes (replica 3), three-way distributed 
         replicated volumes (replica count 3), and arbitrated replicated and 
         distributed arbitrated replicated volumes (replica 3 arbiter 1).
       """

      As this is mentioned under Prerequisites, it gives a sense that this is a mandatory requirement. but we have mentioned same in section: Chapter 6. Recommended Best Practices and Troubleshooting and 3.1. Using Red Hat Gluster Storage Volumes in the Red Hat Virtualization Manager (7. Configure Storage) as well.

      A recommended practice cannot be a prerequisite or vice-versa. 

    3) What should be support statement for sharding: As of now sharding I guess is only supported for RHV use case but I don't see any mention of in our RHV[1] doc. Is this mandatory? If yes, what about existing volumes?


[1] https://access.redhat.com/documentation/en-us/red_hat_gluster_storage/3.3/html-single/configuring_red_hat_virtualization_with_red_hat_gluster_storage
Comment 26 SATHEESARAN 2019-01-31 18:46:18 UTC 
Laura,

1. Contents of virt profile
-----------------------------
There are couple of changes.
The default shard-size is 64MB and its not set explicitly

Contents of virt profile in the document needs to be corrected.

[root@ ~]# cat /var/lib/glusterd/groups/virt 
performance.quick-read=off
performance.read-ahead=off
performance.io-cache=off
performance.low-prio-threads=32
network.remote-dio=enable
cluster.eager-lock=enable
cluster.quorum-type=auto
cluster.server-quorum-type=server
cluster.data-self-heal-algorithm=full
cluster.locking-scheme=granular
cluster.shd-max-threads=8
cluster.shd-wait-qlength=10000
features.shard=on
user.cifs=off
cluster.choose-local=off
client.event-threads=4
server.event-threads=4
performance.client-io-threads=on

2. Section 4.1, point-2 , regarding enabling granular-entry-heal.

In this point, there is recommendation to add the option 'cluster.granular-entry-heal=enable' to virt profile.
This shouldn't be added to virt profile but rather it should be recommended to be set on the volume as:

# gluster volume heal <vol> granular-entry-heal enable


@Laura, could you make these changes ?
Comment 29 SATHEESARAN 2019-02-07 07:41:14 UTC 
Laura,

Could you add 3 more missing volume options in the virt profile ?
Comment 31 SATHEESARAN 2019-02-13 09:31:30 UTC 
The content meets the expectation and moving this bug to verified