[ClusterLabs] Antw: [EXT] Re: Why my node1 couldn't back to the clustering chain?

[Ulrich Windl]

>>> Jason Long <hack3rcon at yahoo.com> schrieb am 09.04.2021 um 08:58 in Nachricht
<2055279672.56029.1617951519012 at mail.yahoo.com>:
> Thank you so much for your great answers.
> As the final questions:
> 1- Which commands are useful to monitoring and managing my pacemaker 
> cluster?

My favorite is "crm_mon -1Arfj".

> 
> 2- I don't know if this is a right question or not. Consider 100 PCs that 
> each of them have an Intel Core 2 Duo Processor (2 cores) with 4GB of RAM. 
> How can I merge these PCs together so that I have a system with 200 CPUs and 
> 400GB of RAM?

If you don't just want to recycle old hardware, you could consider buying _one_ recent machine that has almost all that cores and RAM in one machine, probably saving a lot of power and space, too.

Like here:
 # grep MHz /proc/cpuinfo | wc -l
144
 # lscpu
Architecture:        x86_64
CPU op-mode(s):      32-bit, 64-bit
Byte Order:          Little Endian
Address sizes:       46 bits physical, 48 bits virtual
CPU(s):              144
On-line CPU(s) list: 0-143
Thread(s) per core:  2
Core(s) per socket:  18
Socket(s):           4
NUMA node(s):        4
Vendor ID:           GenuineIntel
CPU family:          6
Model:               85
Model name:          Intel(R) Xeon(R) Gold 6240 CPU @ 2.60GHz
Stepping:            7
CPU MHz:             1001.007
...

# free -h
              total        used        free      shared  buff/cache   available
Mem:          754Gi       1.7Gi       744Gi        75Mi       8.1Gi       748Gi

Regards,
Ulrich


> 
> 
> 
> 
> 
> 
> On Friday, April 9, 2021, 12:13:45 AM GMT+4:30, Antony Stone 
> <antony.stone at ha.open.source.it> wrote: 
> 
> 
> 
> 
> 
> On Thursday 08 April 2021 at 21:33:48, Jason Long wrote:
> 
>> Yes, I just wanted to know. In clustering, when a node is down and
>> go online again, then the cluster will not use it again until another node
>> fails. Am I right?
> 
> Think of it like this:
> 
> You can have as many nodes in your cluster as you think you need, and I'm 
> going to assume that you only need the resources running on one node at any 
> given time.
> 
> Cluster management (eg: corosync / pacemaker) will ensure that the resources 
> 
> are running on *a* node.
> 
> The resources will be moved *away* from that node if they can't run there 
> any 
> more, for some reason (the node going down is a good reason).
> 
> However, there is almost never any concept of the resources being moved *to* 
> a 
> (specific) node.  If they get moved away from one node, then obviously they 
> need to be moved to another one, but the move happens because the resources 
> have to be moved *away* from the first node, not because the cluster thinks 
> they need to be moved *to* the second node.
> 
> So, if a node is running its resources quite happily, it doesn't matter what 
> 
> happens to all the other nodes (provided quorum remains); the resources will 
> 
> stay running on that same node all the time.
> 
> 
> Antony.
> 
> -- 
> Was ist braun, liegt ins Gras, und raucht?
> Ein Kaminchen...
> 
> 
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> me.
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