Linux has at least two other shortcomings on the high end. Clustering
technology for the operating system remains in its infancy, and SAN
capabilities are, for the most part, nonexistent.
Just ask Open Source Initiative leader Eric Raymond. "[Linux]
clustering is still bleeding-edge experimental," he concedes.
TurboLinux has a proprietary clustering product that works well in
informal tests, but most Linux developers would like to see an open-source
solution with better fail-over support.
As is, clustering fail-over support and process migration still needs
work. For today, you should recommend and sell clustered Linux solutions
only if you have a clustering guru on staff. It's not for the faint of
heart or those new to Linux. If your customer demands clustering, IBM's
AIX is likely the better option.
Linux also has weaknesses on the SAN front. The operating system does
not score well when it comes to support for shared-storage options,
whether done with Fibre Channel or SCSI. Work is being done toward both
approaches, but you won't see results from that effort anytime this year.
A related problem is the use and management of logical storage volumes.
As long as the file system is relatively fixed to the physical drive,
neither Linux, nor any other operating system, is going to achieve
six-figure (99.9999 percent) reliability, which is the magic number for
many demanding e-commerce customers.
SGI's Irix file system, XFS, has a logical volume manager that might be
able to divorce logical drives from actual hard drives. In theory, that
will allow resellers to add and subtract physical drives without downtime.
However, XFS's logical volume manager may end up being a proprietary
value-add, according to SGI lead engineer Jeremy Allison. If that is so,
Linux developers will need to hack a solution on their own.
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