[ale] Sportin' SCSI/RAID

[No One]

Let me know if you work this out. I am trying to setup something similar, but I was going
to use SSL on the Apache server for the read/write end. Your setup might be preferred. A
small Apache/MySQL for read/write (not much traffic) and a more powerful Apache/MySQL for
read only (heavy traffic).
TIA Ed.

Jeff Hubbs wrote:

> Eric -
>
> My only real clustering experience is under VMS, in which case the systems do all
> mount the same volumes and in some cases do it over a SCSI channel.  The DEC
> AlphaServers I worked with most recently had outboard RAID controllers and shared a
> set of disks between them, cut up into several RAID arrays.  I'm not trying to
> contradict you, though - I have every expectation that there was some mechanism that
> made one controller or the other "lay out" while one worked the drives.  At the time
> I got laid off, we were working on an Ultra-SCSI-2 SAN connecting three nodes.  But,
> yes, it's looking like in Linux at least, what I'm
> finding is that there's not a similar mechanism, at least not yet.
>
> Actually, I was not looking at this in terms of a cluster per se - I was trying to
> work out a possible arrangement of machines for a public/private Internet Web server
> in which one machine ran Apache and MySQL (but only reading a database) and the other
> ran Apache and MySQL (read/write).
>
> - jeff
>
> "Eric Z. Ayers" wrote:
>
> > Hello Jeff,
> >
> > Most UNIX clustering solutions don't allow both machines to mount the
> > same SCSI target,LUN at the same time.  In fact, the SCSI protocol has
> > this concept called a reservation which explicitly prohibits two host
> > adapters from talking to the same device simultaneously.
> >
> > -Eric.
> >
> > Jeff Hubbs writes:
> >  > Does anyone here have any experience with sharing a RAID array between two
> >  > Linux systems over a common SCSI bus?  What is required?  What are the
> >  > gotchas?  Is it less of a problem if one of the two machines only reads from
> >  > the RAID volume?
> >  >
> >  > If the shared RAID array in question held, say, a MySQL database, how would
> >  > both machines access it (again, presuming one machine only reads)?  An
> >  > instance of MySQL on each system?
> >  >
> >  > - Jeff
> >  >
> >  > ** Happy Holidays to the ALE! **
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