Re: [SSI] Queries related to SSI Linux

[Aneesh K. K.V <ane...@di...>]

Hi, 


On Fri, 2002-10-25 at 19:54, Roopesh wrote:
> Hi,
> 
>         We are evaluating the feasibilty of using SSI Linux as a
> platform
>         for high availability solution. In this regard, we have the
> following
>        architectural queries regarding the SSI Linux.
> 
>         We would appreciate if you can provide any information on these:
> 
> -       What is the maximum number of nodes that is supported in SSI
> without performance 

By default support 15 nodes but was tested and demonstrated with 30
nodes at linux world.

> -       Is Jumbogram support possible for inter node link ?

I did a google serach to find out what is this "Jumbogram" and found 
"  Using the Internet Protocol version 6 (IPv6), a jumbogram is a
transmission packet that contains a payload larger than 65,535 eight-bit
bytes (also known as octets). "

So if it is anything related ti ipv6 then no. internode communication is
based on ipv4. I have seen data structures that are capable of carrying
only 32bits char[4].

But the ICS layer is highly modular and one can implement one using ipv6
. the current implementation can be used as a reference., 

> -       Can fibre channel be used as a lower level transport for ICS ?

IP is the  method used for communication. But as i said above it can be
extended easily. That is what i feel after looking into the code. 


> -       Is broadcast and multicast support available for inter node
> communication ?

I don't think so. But i could be wrong. I am finding separate channels(
socket being opened for lower level nodes to higher level nodes in ICS
). I didn't find anything related to broadcast or multicast. 

> -       Is it possible for one to build a custom messaging service
> within the kernel which uses ICS ? 

If you looking for a kernel based messaging. YES. Take a look at. the
latest ipvs-bind patch i send. It is much simpler and can easily be
understood. BTW a find *.svc on the /usr/src/linux/cluster should give
you more such example. 



> -       Can a  kernel component use low level ICS hooks directly ?
ICS exposes certain API's which can be used by any part of kernel . take
a look at /usr/src/linux/cluster/util/cluster_ksyms.c 

> -       Does the messaging interface available in SSI, provide reliable
> sequenced delivery ?

I guess so. If i get it correctly it uses tcp. But there were some
discussion about UDP. I am not sure about the same. 

> -       In comparison to NSC, what are the different data integrity
> levels supported in SSI linux ?

:)

> -       Is there a clustered volume manager available in SSI-linux ?
> What are its features and what stage 
>         of development is it in ?

See the project page at sourceforge for more information. 

> -       How reliable is SSI linux to address a requirement for building
> a production quality clustering solution 
>         using blade servers ?

Give it a try and decide yourself. :) 

> -       Are there performance figures available for SSI linux
> (especially max
>         data rates on the inter node links) ?

I haven't seen any mail that discuss the same.
> -       Is the performance of SSI linearly scalable on addition of new
> nodes in the cluster ?
> -       What is the plan to provide time synchronization between nodes ?

I guess Roopesh has taken up the work ( That is what i found from the
source forge project page ). But i never heard anything from him on the
list. Is that you ? :) 

> -        Does CFS support failover between the nodes (root & secondary)?

David Zafman is working on this. 

> -        We are considering a configuration where all the nodes can
> directly access the shared disk without
>           being served by a master node. Which is the appropriate
> filesystem layer you suggest (CFS or GFS)?
>  

GFS

> Thanks,
> Roopesh

-aneesh