RE: Re: Media Servers - Big Hard Drives

["Phil Harris" <phil@xxxxxxxxxxx>]

> -----Original Message-----
> From: keyvan2r [mailto:keyvan@xxxxxxx]
> Sent: 19 July 2004 22:16
> To: ukha_d@xxxxxxx
> Subject: [ukha_d] Re: Media Servers - Big Hard Drives

<<SNIP>>

> I just saw this:
>
> http://www.specialtech.co.uk/spshop/catalog/product_531_8_bay_Hard_Dr
> ive_Enclosure_Black.html
>
> It's not clear as to how the 8 drives behave in operation. Is
> each drive connected to a seperate firewire port? Or are they
> seen as one big firewire drive made of 8 ide drives?
> Anyone used something like this? - IDE to firewire external
> drive enclosure
>
> Keyvan

You will see 8 separate drives ... The interface cards have two firewire
ports which are a "firewire in" and a "firewire out".
Firewire can be daisy
chained so you only need one firewire port on your PC which is taken to the
first firewire port on the enclosure, subsequently you loop from one
inteface card in the enclosure to another. (Firewire supports up to a
maximum of 63 firewire "devices" on a firewire interface whether
daisychained or split using a firewire hub - each card would be a firewire
device so you would have four devices daisychained in this case.) Each
interface card supports two hard discs.

I'm just waiting for some "spare funds" (if such things exist) to
order up a
couple of these for myself (I need to re-house 16 x 160Gb drives in a
server
reshuffle which I *MUST* get done soon) . I have been wondering about using
multiple (two or four) separate firewire interfaces in the PC to get better
throughput from these enclosures and also to tidy up cabling a bit, however
I think the multiple port PCI cards are effectively one firewire interface
and an integrated firewire hub so I need to find a firewire card that has
multiple firewire interfaces rather than a single hubbed interface. The
short firewire cables that would be used ideally to loop between interfaces
on the enclosure seem to be exhorbitantly expensive - about twice the price
of a 2m cable! (Little demand for them I suppose.)

On my current firewire enclosures I find I get about 14Mbytes/sec for
writes
and 17Mbytes/sec for reads (real world throughput).

Phil