How to build a SCSI based server serving CDs?
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An Anonymous Coward asks: "Picture this: a mega SCSI based server box with a bunch
of cd-rom drives. What's the best way to build this beast so that it can serve
iso-9660 and hfs CDs to smb/cifs, nfs and appletalk clients? Is there any
particular way to deal with SCSI IDs and LUNs? Is there an easy way to improve
request performance by caching on disk or RAM?"
Use a hard disk :
HD space is really cheap now in comparison. Just copy the CD to the HD and serve it
up from there. I guess this only doesn't apply when you're changing CD's all the
time, but if you're talking about an office jukebox type system then I'd just do
away with the CD's altogether.
Random comments :
There used to be a neat cd-rom server package called 'cdfile' available from
http://www.psocd.com (or http://www.pso.fr ) which would cache files etc so that you could
use the cheap cd changers (I have a Nakamichi 7 disc) unfortunately it was priced
at like $50/disc so it was out of my price range for personal use, and the domain
doesn't seem to exist any more.
If you want lots and lots of cds you might need to use devfs if you run out of
devices. Hardware to look at if you're rolling your own would be the Mylex BT-930
which is a cheap dual channel ultra narrow controller, or maybe the Diamond Dual
Fireport 40 if you can find them. You can also find preassembled cd towers which
translate the scsi ids to LUNs so you get more mileage out of your scsi cards.
http://www.corpsys.com usually sells this sort of stuff, although you pay for it.
We are running a 56 CD Tower from Meridian
( http://www.meridian-data.com/ ),
and a smaller 14 drive one from them.
They came with some crappy Novell emulation type software, we finally got annoyed
enough and went Linux.. The hardware is kind of expensive, but rock solid and cool
looking on the server racks :> Lots of blinky lights when the drives are being
accessed. We have had the smaller tower since end of 94(was not running Linux till
last year) and it have not had any hardware failures..(KNOCK ON WOOD!!)
The bigger tower has a pentium 166, 64 meg of ram and a 1.6 gig HD, the other has a
486sx25, but I was having a problem with IDE controllers on the 486 so I had to
bastardize an old P100 with 16 meg of ram and use that for a controller for the CD
The 166 runs great off of its internal mboard. The smaller tower has 2 Adaptec 1542
scsi cards, the big one has 2 Adaptec 7870's.. the LUNS were all handled by the OS
w/o any hitches at all.. If I remember correctly I did have to manually create the
/dev devices for some of the higher # drives using mknod.
Anyways all the CD's are mounted, then exported via Samba(would be just as easy
with Appletalk and/or NFS) and users are authenticated via our NT Domain.. we went
from 2 to 3 CD lockups a day that had to be manually reset to zero downtime other
than to swap CD's when new ones arrived...... CD's in the tower are only quad
speeds, but performs great from the far side of our network.. seems like it is your
local CD drive... no problems running AVI's and stuff across a couple of 10 meg
One note on performance... 16 meg does not seem to be a problem on the smaller
tower. It dips into its 20 meg swap file occasionally, but I have not noticed any
performance problems..maybe someday I should slap some more memory in it if I think
of it. There are a couple of caching options you can set to really improve Samba
performance on Static file systems.. one is setting get wide cache, and there is
another one I can't think of right now but can look up if you are interested...
they do seem to make quite a diff. on previously accessed CD's.
Anyways upshot of all this typing is that they really rock under Linux... saved us
a bundle over trying to buy the companies "new improved" NT or Novell based access
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performance scsi install
Tip recorded : 16-05-1999 23:08:51
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