even though it might be very theoretical, that only some nodes from the foreign cluster 'll suffer from connection issues, the rule to react up on expel request is
A) if the requested node is really unreachable (or in trouble) ... the node will loose the disk lease after next lease period anyway - so the clsmgr will expel that node
B) if the node is (from the perspective of clsmgr) still healthy ... then the clsmgr decides smth like this
So the "remote" nodes gets expelled first .
please keep in mind... even your local file system / disk access might get in trouble if token revokes/tokem msg can't be send or 're delayed ..
From: "Achim Rehor" <[email protected]>
To: gpfsug main discussion list <[email protected]>
Date: 01/25/2018 11:24 AM
Subject: Re: [gpfsug-discuss] storage-based replication for Spectrum Scale
Sent by: [email protected]
John,
yes, they definitely can!
Nodes in a remote cluster are tob viewed just as local nodes in terms of taking part in the mechanisms of access to data.
Token management will be done just as with local nodes.
So if one node in cluster A recognizes a communication issue with a node in cluster B, it will let the clustermgr know,
and that one then decides on whether to expel one or the other.
Having a remote cluster connected relies on a stable and low latency network, just as a local cluster does.
if your network is not reliable, you woudl go for AFM or other replication mechanisms (as the thread title implies;) )
Mit freundlichen Grüßen / Kind regards
Achim Rehor
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From: John
Hearns <[email protected]>
To: gpfsug
main discussion list <[email protected]>
Date: 25/01/2018
10:53
Subject: Re:
[gpfsug-discuss] storage-based replication for Spectrum Scale
Sent by: [email protected]
Jan Frode, thankyou for that link.
I have a general question regarding remote GPFS filesystems.
If we have two clusters, in separate locations on separate Infiniband fabrics,
we can set up a remote relationship between filesystems.
As Valdis discusses, what happens if the IP link between the clusters goes down or is unstable?
Can nodes in one cluster vote out nodes in the other cluster?
From: [email protected] [mailto:[email protected]] On Behalf Of Jan-Frode Myklebust
Sent: Wednesday, January 24, 2018 8:08 AM
To: gpfsug main discussion list <[email protected]>
Subject: Re: [gpfsug-discuss] storage-based replication for Spectrum Scale
Have you seen https://www.ibm.com/support/knowledgecenter/en/STXKQY_4.2.0/com.ibm.spectrum.scale.v4r2.adv.doc/bl1adv_dr.htm? Seems to cover what you’re looking for..
-jf
ons. 24. jan. 2018 kl. 07:33 skrev Harold Morales <[email protected]>:
Thanks for answering.
Essentially, the idea being explored is to replicate LUNs between identical storage hardware (HP 3PAR volumesrein) on both sites. There is an IP connection between storage boxes but not between servers on both sites, there is a dark fiber connecting both sites. Here they dont want to explore the idea of a scaled-based.
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