[Pvfs2-users] Re: Multiple data stores on one machine

[Murali Vilayannur]

Hi Steve,

Looks good. See inline comments below...

> <Aliases>
>  Alias caos1 TCP://caos:3334
>  Alias caos2 TCP://caos:3335
> </Aliases>
> <Filesystem>
>  Name pvfs2-fs
>  ID 699094865
>  RootHandle 1048576
>  <MetaHandleRanges>
>   Range caos1 4-214748365>
>  </MetaHandleRanges>
>
>  <DataHandleRanges>
>
>   Range caos1 2147483651-4294967297
>
>   Range caos2 4294967298-6442450944
>
>  </DataHandleRanges>
>
>  <StorageHints>
>
>   TroveSyncMeta yes
>
>   TroveSyncData no
>
>  </StorageHints>
>
> </Filesystem>
>
>
>
> /etc/pvfs2-server.conf-caos1
>
> StorageSpace /pvfs2-storage-space

(^) See the comment on why it is a bad idea to share storage spaces below...

>
> HostID "TCP://caos:3334"
>
> LogFile /tmp/pvfs2-server.log
>
>
>
> /etc/pvfs2-server.conf-caos2
>
> StorageSpace /pvfs2-storage-space

^^^^^^^^
Please don't use the same storage space for 2 different pvfs2-server
processes on the same node! They may end up trampling over each other.
I thought the whole point of what you were trying to do was to add
some new storage space/drives to the pvfs2 volume!! :)
>
> Pvfs2-server /etc/pvfs2-fs.conf /etc/pvfs2-server.conf-caos1 -f
>
> Pvfs2-server /etc/pvfs2-fs.conf /etc/pvfs2-server.conf-caos2 -f
>
>
>
> Then started 2 servers
>
>
>
> Pvfs2-server /etc/pvfs2-fs.conf /etc/pvfs2-server.conf-caos1
>
> Pvfs2-server /etc/pvfs2-fs.conf /etc/pvfs2-server.conf-caos2
>
>
>
> Is that correct that I need to run 2 server daemons ?

Yes! Running both the daemons is correct..

> The mount command then seems a little confusing
>
> Mount -t pvfs2 TCP://caos:3334/pvfs2-fs /mnt/pvfs2
>
> As you only reference one port.

This is probably documented somewhere, but it is possible to use any
of the servers for mounting!!
All you need to pass is a valid bmi url for a valid config server, so
in this case
mount -t pvfs2 tcp://caos:3335/pvfs2-fs /mnt/pvfs2
would also have worked fine.

> In this instance I started with genconfig editing the files to get a
> starting point. Can you explain the numbers and how a would choose the range
> to add another files store ? Is it a simple as calculating the difference
> from one range and adding that to last one used ?

Yes it is! Just make sure that no handle ranges overlap with each other.
For fairness, it would be best if all servers see roughly the same #
of handle ranges
so that the handle allocator can fairly disperse the handles to all the servers.
Hope this explains all your questions,
thanks,
Murali

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> Steve
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