[LUDOC-31] servicenode is not documented

• Status: Closed
• Project: Lustre Documentation
• Type: Improvement
• Priority: Minor
• Reporter: Richard Henwood (Inactive)
• Assignee: Jessica A. Popp (Inactive)
• Resolution: Fixed

Description

--servicenode is not documented in the manual

Comments

[Richard Henwood (Inactive)]

I have just had a chat with Brian on this topic, the conversation went as follows:

B historically, when one formats a target with a failnode and then registers it, the node it was registered from and the fail node are both written as locations for the target.
when you use --servicenode the node you register from is no longer listed as a service node but the listed --servicenodes are.
B this makes it possible to register the target somewhere other than where you intend it to run, for example.
B so imagine --servicenode as being the merging of --failnode and (a fictitious and implied) --register-from-node parameter. if that makes sense.
B imho, --servicenode is superior and less confusing than the old implict +--failnode behaviour.
B since it makes absolutely clear which nodes will be service nodes and doesn't hide one of them as the node being registered from.
B and it also doesn't require a specific one (or any, iiuc) of the service nodes to be up in order to register the target
Me what is a service node?
B a node that provides service for the target
B i.e. an OSS or MDS
Me is Active-Active failover an example of when you would want to register an target without a service node?
B so normally if you have two nodes (A and B) for a target you do:

A # mkfs.lustre ... --failnode B /dev/sda
A # mount -t lustre /dev/sda /mnt
with service node you (can) do:
C # mkfs.lustre ... --servicenode A --servicenode B
C # mount -t lustre /dev/sda /mnt

B and nodes A and B will be configured as the nodes that hosts go to for that target
J the service node option is just a way to control what nids are registered to the mgs

[Zhenyu Xu]

manual update tracking at http://review.whamcloud.com/1904

[Richard Henwood (Inactive)]

Excellent! Thanks for getting on this so quickly!

[Richard Henwood (Inactive)]

Bobijam's manual update has landed.