[gpfsug-discuss] AFM gateway node scaling

[Venkateswara R Puvvada]

Matt,

It is recommended to have dedicated AFM gateway nodes. Memory and CPU 
requirements for AFM gateway node depends on the number of filesets 
handled by the node and the inode usage of those filesets. Since AFM keeps 
track of changes in the memory, any network disturbance can cause the 
memory utilization to go high and which eventually leads to in-memory 
queue to be dropped. After the queue is dropped, AFM runs recovery to 
recover the lost operations which is expensive as it involves creating the 
snapshot, running policy scan, doing readdir from home/secondary and build 
the list of  lost operations. When the gateway node goes down, all the 
filesets handled by that node distributed to the remaining active gateway 
nodes. After the gateway node comes back, filesets are transferred back to 
the original gateway node. When designing the gateway node, make sure that 
it have enough memory , CPU resources for handling the incoming and 
outgoing data based on the bandwidth. Limit the filesets per gateway(ex. 
less than 20 filesets per gateway)  so that number of AFM recoveries 
triggered will be minimal when the queues are lost. Also limit the total 
number of inodes handled by the gateway node across all the filesets (ex. 
less than 400 million inodes per gateway).  AFM gateway nodes are licensed 
as server nodes.


~Venkat (vpuvvada at in.ibm.com)



From:   Matt Weil <mweil at wustl.edu>
To:     gpfsug-discuss at spectrumscale.org
Date:   03/23/2020 11:39 PM
Subject:        [EXTERNAL] [gpfsug-discuss] AFM gateway node scaling
Sent by:        gpfsug-discuss-bounces at spectrumscale.org



Hello all,

Is there any guide and or recommendation as to how to scale this.

filesets per gateway node?  Is it necessary to separate NSD server and
gateway roles.  Are dedicated gateway nodes licensed as clients?

Thanks for any guidance.

Matt

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