[Bioclusters] file server for cluster

William Park bioclusters@bioinformatics.org
Fri, 19 Apr 2002 01:12:48 -0400

On Thu, Apr 18, 2002 at 09:35:10PM -0400, Ivo Grosse wrote:
> William Park <opengeometry@yahoo.ca> wrote on Thu, 18 Apr 2002:
> > For IDE solution, 8 x 120GB 
> What about 6 x 160 GB???

That works too, I guess, though I can't speak about ATA133 from personal
experience.  80GB is cheapest per GB, now; but, you would need 12 of them.
I guess you can put them all on 6 channels.  Of course, you know the
problem with that.

You can go with 6 x 180GB Seagate harddisk.  This will be the cheapest SCSI
solution per GB, and 6 disks will be no problem for SCSI.  Just bear in
mind that
    - PCI bandwidth is 133MB/s (100MB/s realistically).
    - single-channel U160 over 6 disks means 25MB/s if all disks get
      accessed simultaneously; dual-channel can give you 50MB/s.
    - 100Mbit ethernet means 10MB/s --> so all other arguments becomes

SCSI is not a bad option.  You get to use commonly available case,
motherboard, cards, and other components.  Whereas IDE option is a bit
leading edge and not too common.  You have to worry about drivers,
stability, upgrade, etc.

When everything is said and done, your choice will depend on who is writing
the cheque.  There are those who will go into finer details of how to split
a hair, but they usually spend someone else's money and expect to get paid
for it.  If you are purchasing with your own money, then your perspective
will be similar to mine.

> > is ideal because you can use 2 channels from the motherboard and 6
> > channels from Promise card.  If backup is not of an issue, then you can
> > put 2 disks on the same IDE channels and you only need 4 IDE channels.  
> Wait.  We got quoted 6 x 160 GB now, with the option of 12 x 160 GB in
> the future, so 6 bays are currently open.  Do I understand it correctly
> that we could not backup the data if all 12 bayes were populated???

The issue of backup is tricky.  You can 
    - setup a spare server just to hold the data, 
    - install another set of harddisk into the same case, or
    - do traditional tape backup.  

If you go with SCSI, then backup becomes easier since SCSI can handle
multiple disks much easier.  Perhaps, you would save money here, offsetting
cost in other places.  There are commercial cases with upto 22 bays.

Main problem with IDE solution is that connecting all 6 or 12 disks with
only 18" IDE cable gets complicated very fast.

William Park, Open Geometry Consulting, <opengeometry@yahoo.ca>
8 CPU cluster, NAS, (Slackware) Linux, Python, LaTeX, Vim, Mutt, Tin