Marc Zampetti wrote:
> I have a cluster on two hosts with 4 data nodes. I want to test using
> shared memory links for the data nodes that are on the same hosts. What
> is the correct way to enable shm links for this setup, including any
> OS-level configurations. All of the nodes are running as the "mysql"
> user, and this is on CentOS 5 64-bit. I'm starting the cluster from
> scratch, with no data.
Hi Marc,
You're probably not going to like this answer very much, but right now
we don't really support SHM configuration and can make no guarantees if
it even works in any given release.
Also, as it says here
http://dev.mysql.com/doc/refman/5.1/en/mysql-cluster-shm-definition.html
our own testing suggests that there's really no performance or any other
advantage to using the SHM transporter over TCP/IP.
I spoke about this with one of our developers, and he says (more or
less), that currently SHM is really only of interest if you're prepared
to go digging into the code and possibly fixing it yourself.
Sorry.
Thanks!
jon.
>
> Setup
>
> host 1 - data node id 2, data node id 4.
> host 2 - data node id 3, data node id 5.
>
> config.ini
>
> [NDBD DEFAULT]
> NoOfReplicas=2
> Datadir=/db/data/cluster
> FileSystemPathDD=/db/data/cluster
> #FileSystemPathUndoFiles=/db/data/cluster
> #FileSystemPathDataFiles=/db/data/cluster
> DataMemory=3072M
> IndexMemory=1024M
> LockPagesInMainMemory=1
> DiskLess=1
>
> [shm default]
> SigNum=10
>
> [ndbd]
> Id=2
> Hostname=host1
>
> [ndbd]
> Id=3
> Hostname=host2
>
> [ndbd]
> Id=4
> Hostname=host1
>
> [ndbd]
> Id=5
> Hostname=host2
>
> [shm]
> NodeId1=2
> NodeId2=4
> ShmKey=2424
>
> [shm]
> NodeId1=3
> NodeId2=5
> HsmKey=3535
>
> Some questions that I have.
> 1) Do I need to define links for each direction. I.e. do I need to have
> a [shm] section for NodeId1=2, NodeId2=4 and another [shm] section with
> NodeId1=4 and NodeId2=2? If so, do I need to define a separate Shmkey,
> or use the same key? Any other things I need to configure? What order do
> I need to start things in? Is it different then normally?
>
>
--
Jon Stephens - jon.stephens@stripped
Technical Writer
MySQL Documentation Team
Sun Microsystems AB
MySQL and Software Infrastructure Group
Liljeholmen (Stockholm), Sweden
Summer: UTC +02.00 / Winter: UTC +01.00
Mobile: +46 (0) 736 773 993
Skype: plastic-fish
MySQL: www.mysql.com
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