The original message:
A vendor is configuring a system for us. We are getting a rackmounted
2100/275 server. For data fault tolerance, we are getting two BA350 enclosures
each having three rz28s and there will be two storage controllers. The three
disks will be striped and each striped set of disks will be mirrored (the disks
in one enclosure mirror the other enclosure's disks).
The vendor is saying that we need Logical Storage Manager (which will stripe
and mirror the disks) and we need raid controllers. I'm not an expert (they
are),
buy I think that is redundant. I pertain that all we need is LSM and two
KZPAA controllers (which much less expensive) because the LSM is hardware
independent
in doing the stripig and mirroring. The LSM license is free for us (due to the
CSLG educational program we subscribe to) as is the Advanced File System
Utilities I would use instead of ufs filesystems.
Whose right? Can't we stripe and mirror via LSM over two PCI (not RAID) storage
controllers and save money? Are there other considerations, like performance,
that should affect the controller type decision?
Summary of Responses:
LSM is hardware independent and uses the cpu to create and send out
multiple disk requests. The RAID controller is not required.
The benefit of using RAID controllers is that you would probably get
higher I/O rates with less CPU overhead.
The true issue, as people pointed out, is: Will LSM degrade performance
sufficiently that the configuration will not meet the vendor's performance
benchmarks? If it does degrade performance too much for our usage, then
we have to look into other solutions using RAID controllers or the new
fast-wide-differential SCSI controllers. We must also keep in mind that
there are fewer PCI slots than EISA slots and we may not want to use up
the PCI slots.
Thanks for everyone who replied. Now my configuration discussion with the
vendor can progress beyond the vendor stopping me and saying "trust me".
Bob Berrigan
Kent School District
Kent, WA
Received on Thu Apr 20 1995 - 14:36:15 NZST