Bug 1400436

Summary: [Async] JBOD section of the admin guide needs update
Product: Red Hat Gluster Storage Reporter: Anjana Suparna Sriram <asriram>
Component: doc-Administration_GuideAssignee: Divya <divya>
doc-Administration_Guide sub component: 3.1 Release QA Contact: Prasad Desala <tdesala>
Status: CLOSED CURRENTRELEASE Docs Contact:
Severity: unspecified    
Priority: unspecified CC: asriram, asrivast, mpillai, rcyriac, rhinduja, rhs-bugs, sasundar, storage-doc
Version: rhgs-3.1Keywords: ZStream
Target Milestone: ---   
Target Release: RHGS 3.1.3 Async   
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: 2016-12-26 13:00:22 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:

Description Anjana Suparna Sriram 2016-12-01 09:05:43 UTC 
Describe the issue:  I got an interesting question from a customer.

Why is "JBOD" the only supported disk type for RHGS 3-Replication Vol ?

My guess is
 - Performance : RAID-6 disk will add extra latency on top of 3-replication perf degradation (compared to 2-replication). 
 - Usable capacity : RAID-6(10+2) 83% X 3-Replication 33% = 27% 

Anyone has idea on this ?


Suggestions for improvement: Sayan sent a request over email to update this section: 

I think we should fix the above to say that "It is recommended that 3-way replicated volumes use JBODs but RAID-ed 3-way replicated volumes are also supported".

Thanks
Sayan

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Alok: 
Few comments:
All other content related to JBOD, 3-way and RAID needs to be in sync. Fo example, section 13.1.2 talks about JBOD with 3-way and no RAID.
Since our testing happens mainly with RAID 6 and RAID10 to some extent, we should provide link to the relevant sections in the doc.
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To elaborate, This is what section 13.1.2 says:

"In the JBOD configuration, physical disks are not aggregated into RAID devices, but are visible as separate disks to the operating system. This simplifies system configuration by not requiring a hardware RAID controller."

This is in contradiction to the new addition where we say "It is recommended that three-way replicated volumes use JBOD, but RAID-ed three-way replicated volumes are also supported."
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Comment 5 Divya 2016-12-02 09:55:36 UTC 
I have received an ACK from Alok over an email. Hence moving the bug ON_QA.

Following sections have been updated:

- Updated supported storage info in the 6.7.2. Creating Three-way Distributed Replicated Volumes section http://jenkinscat.gsslab.pnq.redhat.com:8080/view/Gluster/job/doc-Red_Hat_Gluster_Storage-3.1.3-Administration_Guide%20(html-single)/lastSuccessfulBuild/artifact/tmp/en-US/html-single/index.html#Creating_Three-way_Replicated_Volumes

- Updated supported storage info in the 6.6.2. Creating Three-way Replicated Volumes section http://jenkinscat.gsslab.pnq.redhat.com:8080/view/Gluster/job/doc-Red_Hat_Gluster_Storage-3.1.3-Administration_Guide%20(html-single)/lastSuccessfulBuild/artifact/tmp/en-US/html-single/index.html#Creating_Three-way_Distributed_Replicated_Volumes

- Added an important note in the 6.8. Creating Dispersed Volumes section http://jenkinscat.gsslab.pnq.redhat.com:8080/view/Gluster/job/doc-Red_Hat_Gluster_Storage-3.1.3-Administration_Guide%20(html-single)/lastSuccessfulBuild/artifact/tmp/en-US/html-single/index.html#chap-Red_Hat_Storage_Volumes-Creating_Dispersed_Volumes_1 

- Added an important note in the 6.9. Creating Distributed Dispersed Volumes section http://jenkinscat.gsslab.pnq.redhat.com:8080/view/Gluster/job/doc-Red_Hat_Gluster_Storage-3.1.3-Administration_Guide%20(html-single)/lastSuccessfulBuild/artifact/tmp/en-US/html-single/index.html#sect-Creating_Distributed_Dispered_Volumes_1

- Updated the ⁠13.1. Disk Configuration and 13.1.2. JBOD sections  http://jenkinscat.gsslab.pnq.redhat.com:8080/view/Gluster/job/doc-Red_Hat_Gluster_Storage-3.1.3-Administration_Guide%20(html-single)/lastSuccessfulBuild/artifact/tmp/en-US/html-single/index.html#sect-Disk_Configuration
Comment 6 Prasad Desala 2016-12-05 11:30:28 UTC 
Verified the links provided in comment 5 and the changes looks good.
Moving this BZ to Verified.