Organization: PC-OHIO BBS - Cleveland, OH - 216-381-3320
Newsgroups: bit.listserv.novell
Date:         Thu, 7 Jan 1993 11:28:00 LCL
Reply-To:     Bob Abbott <bob.abbott@pcohio.wariat.org>
From:         Bob Abbott <bob.abbott@PCOHIO.WARIAT.ORG>
Subject: Re: Server Fault Tole

N>From:         Netman@PHYSLOG-PO.PHYSLOG.UIOWA.EDU
N>Subject:      Re: Re: Server Fault Tolerant H/W Sources Sought

N>I am looking at RAID as well as SFT III.  But the RAID solutions
N>I've seen so far are pricey and they only address the storage
N>component of the server.  If the power supply, the controller, or

  Take a look at duplexing instead of RAID5.  In a tech seminar, a
Novell SE said duplexing accomplishes the same thing as RAID 5 at a much
lower cost.  Cost it out on paper.  Even tho' the duplexing only gets
50% utilization of capacity vs. maybe 75% for RAID, you aren't taking a
hit on the premium of the fat RAID software/hardware "royalties."  The
duplexed drives can almost be hot swapped by unmirroring, unload
driver, install new drive, load driver, run install to make new
volumes, mount and remirror.

N>So one machine hums away as a very impressive server and the
N>other sits alongside my desk and makes my programming tasks a
N>little more pleasant.

N>So what are the tradeoffs?  I can't insure that every last
N>transaction will be safe.  I stand the chance of seeing a disk
N>error bring down the network for a few hours.  I could end up
N>programming on a Model 50Z for a week.  In return, I have a
N>broader insurance policy that covers the whole server.  I have an
N>additional productive piece of hardware (if the server never
N>fails -- knock wood-- I'll still have gotten my mileage out of
N>the spare.)  And I have saved a mint. (Well, actually the
N>difference between a $14,000 RAID and a $4,500 spare server.)

  And you are correct about the second server.  With duplexing on the
primary server, you have redundancy on one of the least reliable parts,
hard drive with it's moving parts.

  Other thoughts...  At Comdex, PC Power and Cooling had a case with
redundant power supplies and a distribution board that shares power
supplies and switches everything over to one in case of failure.  Theory
is to run PS at less than 50% gaining life, keeping "spare" (either PS)
working and yet have the capacity to run on one only.

  Another thought...  ArcServe has capability to mirror volumes between
servers.  I haven't tried it, but it looks like a "poor man's SFT III"
without the $20,000 hit for Novell's software.  Configure the second
server with a runtime (if you can get it) or 5 user 3.11 (about same
price).  ArcServe would mirror files and prune out old ones so they
match.  Would maybe be a half hour behind in sync.  Not a bad setup with
duplexed drives and mirrored volumes.  If the first server dies, just
boot second server with the first server's SERVER.EXE.  Mount drives in
plug-in drawers (< $100 each) and you can swap the drive also.  Not
TOTALLY SFT III, but 98% functionally the same.

N>I hope I haven't waxed to lengthy..

  Likewise.

N>P.S.  Anyone who sees big gaping holes in my strategy is stongly
N>encouraged to ruin my day. (Better than I should find out in
N>practice.) Other tips and suggestions would be most welcome.

  Well, this is the place to display the thoughts.  Anyone try ArcServe
for mirroring?  Any other ideas for "poor man's SFT III."


Bob Abbott          Internet: Bob.Abbott@pcohio.wariat.org
                              cj145@cleveland.freenet.edu
                    FidoNet:  1:157/511
                    MHS:      BOB @ TECHSERV via NHUB

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