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NCS Replication and Recovery

ETG team - DeliveryRally US 137332

Rajesh Tripurneni

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Replication Analysis Questions

• How will teams at remote sites handle the following operations in a streamlined and efficient way?:- Pulling down the entire code base (cloning)- Pulling down the latest changes (pulling)- Pushing changes into the “master” origin

• How can we use replication to help us with disaster recovery or other outages?

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Option 1 – Single Pull/Push Site

• Remote sites pull from and push to the master origin (RCDN).

• Advantages- Only one source to get the code from

• Disadvantages- Takes a long time to pull down the code- Requires a lot of bandwidth to pull down the code

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Option 2 – Remote Tracking Branch (RTB)

• Create a RTB in RCDN to help control commits

• Advantages

• Disadvantages- Not recommended or supported by the SCMCI team (http://

wikicentral.cisco.com/display/PROJECT/High+availability+with+Git+using+Remote+Branch+Tracking)

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Option 3 – Cloned Repos at Remote Sites

• Remote sites pull from a remote origin at their site and push to the master origin (RCDN).

• Advantages- Pulling down the code is faster, since the clone is local- Having only one Gerrit location to push to reduces or

eliminates synchronization errors in the master repos

• Disadvantages- More setup involved

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Option 4 – Separate Repo Setup at Remote Sites

• Remote sites pull and push from a remote origin at their site. Periodic pushes occur between the remote origin and the master origin.

• Advantages- Pulling down and pushing back code is faster, since the

origin is local

• Disadvantages- Synchronization problems- Increased merge conflicts

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Recommended Solution (Option 3)

Developer workspace (US)

Developer workspace (BGL)

NCS Gerrit Server (RCDN)

gpull

gpullt

rig

ge

r

gpush

gpush

merge

NCS repos(master copy)(RCDN)

git

pull

NCS repos(clone)(BGL)

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Recommended Solution for Recovery

NCS repos(master copy)(RCDN)

NCS repos(clone)(BGL)

NCS repos(clone)(RTP)

NCS repos(clone)(SJC)

git pull

git pull

git pull

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Option 3 – Implementation Considerations

• Replication for Code Development- Update the gpull and gpush wrapper scripts so that they

automatically pull and push from the correct origins, based off of the user’s location

- Set up a Gerrit trigger on the NCS Gerrit server which notifies remote clones to initiate a git pull, so that they can be updated

• Replication for Recovery- Reach out to the SCMCI team to help get IT supported Git

clones set up (http://wikicentral.cisco.com/display/PROJECT/SCMCI+-+Centrally+Supported+Git)

- Set up a polling or transaction based method of updating the Git clones

Thank you.