Grant,
I agree with Ian! I think you're heading for major pain.
You should not mount filesystems simulataneously!
Have a read around for cluster (or global) filesystems.
Some names that come to mind are coda, gfs or the latest
(and greatest?) is inter-mezzo
I have used that setup under solaris, but that was using
solaris8's cluster 3 software which used their gfs.
Regards,
-Matt
Wienand Ian wrote:
> firstly what file system are you using? i can't see this working with any
> standard non distributed file system.
>
> i've never seen anything like this -- two pc's essentially using a single
> disk. but everything makes me think that this would not be a good solution
> as i can't think of any file system that was developed to be used like this.
> the problem is one of abstraction; the scsi bus handles putting blocks onto
> the disk, and that is all. the os filesystem functions organise those
> blocks into an entity that is file system. a user space protocol and
> daemons such as NFS can handle multiple accesses and sort them out for
> handing down the chain.
>
> i can't see how this setup can guarantee normal unix semantics ; i.e. a read
> after write returns the value just written and two writes returns the latest
> write. if this fails, then so does everything built ontop of it. why you
> can't see updates i don't know, but i think that would only be a symptom of
> a larger problem.
>
> for what it's worth, i can't see this working without some sort of
> distributed file system, e.g. nfs or samba. failing that, you would have to
> write your own file system that implements some sort of session semantics,
> immutable files or atomic transactions or some other scheme you think of
> yourself. sounds like fun but probably not the easiest way to solve the
> problem.
>
> i'm happy to be corrected on any of the above points, however.
>
> -i
>
>>-----Original Message-----
>>From: Grant Parnell [SMTP:[EMAIL PROTECTED]]
>>Sent: Thursday, April 18, 2002 10:40 AM
>>To: [EMAIL PROTECTED]
>>Subject: [SLUG] Sync of filesystem on multiple SCSI hosts
>>
>>I have a client with the following setup:
>>
>> __________________
>> | |
>> | Firewire storage |
>> |__________________|
>> | |
>> | |
>> ________|_ _|________
>>| | | |
>>| Server A | | Server B |
>>|__________| |__________|
>>
>>This is not an NFS mount, the box has multiple SCSI buses.
>>
>>Both Server A and Server B mount the same filesystem and my client says
>>that when files are written by Server A the only way they can be seen on
>>Server B is to unmount the filesystem and re-mount it. I did suggest using
>>the sync option when mounting the filesystems and also trying the sync
>>command but this didn't help.
>>
>>Effectively we need to lose the linux filesystem buffers (and yes, all the
>>efficiency that goes with that) I think but I don't know how to do that.
>>
>>Possibly this could be done periodically on each server to allow some
>>level of filesystem efficiency but I'm guessing this would be more
>>trouble.
>>
>>If this isn't easy I'm going to have to suggest NFS... wonder if you can
>>do NFS over SCSI? I've heard of TCP/IP over SCSI I think. I do not know if
>>the Servers can see each other on the SCSI buses, certainly not visible in
>>/proc/scsi areas so my guess is no.
>>
>>--
>>---<GRiP>---
>>Grant Parnell - senior consultant
>>For all your Linux Commercial quality support and consulting needs
>>Web: http://www.linuxhelp.com.au Email: [EMAIL PROTECTED]
>>For retail sales see http://www.everythinglinux.com.au
>>Phone 02 8753 0792 to book service.
>>
>>--
>>SLUG - Sydney Linux User Group Mailing List - http://slug.org.au/
>>More Info: http://lists.slug.org.au/listinfo/slug
>
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