mount r/w and r/o

Jérôme Petazzoni jp at
Fri Nov 4 17:11:04 UTC 2005

[one r-w mount, multiple r-o mounts shared thru FC switch]

>>>should I use it?
>>>Am I going about this all wrong, is there a better way to do this 
>>>(other than GFS)?
I once heard about someone doing something like that for a video farm, 
intermixing solaris and freebsd servers (so as far as he, and I, knew, 
there was no easy sharing solution). He did the following :
- create the filesystem on the solaris bow
- create many 1 GB files, with a specific byte pattern (512 bytes 
sectors iirc)
- the freebsd box would read the raw device, detect the byte patterns 
and build an internal lookup table, to know that file F, offset O was 
located on physical sector S
- the solaris box would then write data to the 1 GB files, and the 
freebsd box could then read back the data, thanks to the previously 
built lookup table (the 1 GB files would only be rewritten to, never 
truncated or rewritten, AFAIK)

IIRC, there was 2 solaris boxen using some HA solution, and many freebsd 
boxen accessing the data. This worked because the files were smaller 
than 1 GB (to be honnest, I don't know the exact size he used), and the 
very impressive performance of the solution balanced the hassle involved 
in setting up the whole thing.

Now, I would not ask "why not NFS?", but "why not GFS?" (and please 
apologize if it the answer is obvious...)

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