Fileserver/SCSI/Network Drives questions.

[Zepher]

I've got a bunch of SCSI drives, half of them are 80pin with adaptors and the other are 68pin.
The drives are used for data storage, mainly movies which are shared over the network.

With my current case setups, I can't get all the drives into all the machines, not enough physical space, each machine has 4 drives in it already (excpept for the linux box).

I just got a SCSI box but it is the 50pin SCSI type.
So, how much speed will I be sacrificing by using 68 to 50 pin adaptors and putting those drives into this case?
The machine that the case will be attached to is the P3 450 with an Adapted UW & U2W controller on it that I use as a network drive server, there is no kb, mouse, or monitor attached to it, I access it with TightVNC if I need to do anything with it.

what would you do?

 

[Anarchy]

50pin is limited to 20MB/s i's say ... but a 100MBit Network is limited to 12MB/s so that shouldn't be a prob

But the cable lenght could be one ... non-LVD can be up to 1.5m and LVD up to 15m

I had something like that running with 6 9GB Drives in an external case but i've replaced the original 50pin cable with a LVD 68pin Cable i bought on eBay and use a LVD external cable too ...

 

[J Macker]

it depends on which interface the connectors are. and what the hard drives are capable of.
refer to here:
http://www.transintl.com/technotes/scsi.htm

different types of 50 pin connector data transfer rates:
ultra scsi (20mb/sec)
ultra2 scsi (40mb/sec)

68-pin interface transfer rates:
fast wide scsi = 20mb/sec
ultra wide scsi = 40mb/sec
ultra 2 wide scsi (U2W) = 80mb/sec
U160 = 160mb/sec
U360 (the newest) = 360mb/sec

Note that this is the total bandwidth on the entire length of cable. If you have 4 drives on one cable, and you have an operation requiring only one drive and it's pushing 20mb/sec and your total cable bandwith is 20mb/sec, then as soon as another drive starts operating, the cable (and bus speed) become the bottleneck instead of hard drive transfer speeds.

Also, remember that the scsi bus speed is determined by the slowest drive on the chain.
reading more and looking at data transfer rates for the atlas 10k drive from maxtor, shows max burst transfer speeds of 96mb/sec and sustaining 72/mb sec.

either way, the data transfer rates aren't going to matter a whole lot since the bottleneck in your application is network speeds. If you have a Gigabit network, your max transfer rates are 119.2MB/sec

if you have 10/100 ethernet and are using 100Mbps rates, your max transfer rates are 11.92MB/sec

Considering that I don't know how fast your network is, or what speed the SCSI bus will be running at, I can't offer a setup suggestion for what I would do.

 

[Anarchy]

@J Macker - very nice post ... but it's U320 not U360

 

[Zepher]

Thanks for the response.
My network is running at 100mbps.
The drives that are going into the case are all Seagate 18gig barracudas and one 10K 18gig Fujitsu, I believe they are all UW SCSI

The shortest 68 to 50 pin external cable I have is 6 feet, and the internal 50pin ribbon in the drive case is probably 3 feet. The internal cable in the server to the motherboard is appox 18 inches.

I did a test a week ago to see how many machines can access the files at the same time and I was able to serve one divx movie (700megs) to 7 machines, all playing from a different location in the movie.
I also did a test playing 7 different movies from the same drive and it worked great too. All files were playing off of one of the cheetahs that is running off of the U2W connector on the motherboard.