We are looking at storing data on a fileserver. The data is mission
critical.
Currently data is stored locally but it is messy getting the
data off the various disks that make up the total system.
Apart from collecting data there is also real-time control which is
as mission critical.
What combination is recommended or maybe have you worked on?
I suppose it would be best to use the latest versions of QNX6?
What is the trade-off between NFS & CIFS?
I suppose also what will be involved is the performance and
reliability of the NIC? Any recommendations?
We are looking at storing data on a fileserver. The data is mission
critical.
Currently data is stored locally but it is messy getting the
data off the various disks that make up the total system.
Apart from collecting data there is also real-time control which is
as mission critical.
What combination is recommended or maybe have you worked on?
I suppose it would be best to use the latest versions of QNX6?
If your system is involved in anything mission-critical, you don’t want a
slightest chance of getting it messed up due to network failures or anything
of that sort. You need to split the data writing into two phases - local and
remote, and make them asynchronous.
A good solution would involve a “logger” service. It would look like a
resource manager that presents mission critical part of the system with
“virtual” files that in reality are circular in-memory buffers. The other
part of the service would talk to whatever remote storage is available to
drain the buffers whenever appropriate.
The point is that writing those data should never fail as far as
mission-critical part of the system is concerned. Since the data is also
mission-critical, the service would have to monitor buffer levels and raise
alarms and/or take whatever actions you can if the buffers are not being
drained fast enough to sustain operations. In the worst case you have to
decide what is more critical - the system or the data and perhaps allow the
buffers to wrap around for lack of better options.
We have developed a system like that for billing purposes.
What is the trade-off between NFS & CIFS?
NFS can work over UDP, which may be an advantage depending on your network.
CIFS has advantage of being natively supported by Windows.
I suppose also what will be involved is the performance and
reliability of the NIC? Any recommendations?
Anything of “server” kind with deeper buffers and checksum-offloading.
Intel gigabit server NICs. Or even 100Mb Speedos (Intel 82559).
Thanks Igor-you raise good points here.
The current solution is aynch but using ftp & IDE which
is not good enough as the file transfer potentially
interferes with the realtime process.
The challenge is in the volume of data-but that might be solved
by throwing enough RAM at it.
I would like to do away with the local disks somehow,
and only let it deal with providing non-volatile storage.