firewire question

O

Oldspook

I have one WD 250GB external hard drive connected by firewire. It performs
well and is very fast for an external drive. I turn the drive off when I
don't need to access its data.

I plan on buying 2 more of the same drive and connected them daisy chained
to the firewire. With 3 drives daisy chained will I be able to keep the
drives off and only turn on the one I want to access?
 
N

Neill Massello

Oldspook said:
I have one WD 250GB external hard drive connected by firewire. It performs
well and is very fast for an external drive. I turn the drive off when I
don't need to access its data.

I plan on buying 2 more of the same drive and connected them daisy chained
to the firewire. With 3 drives daisy chained will I be able to keep the
drives off and only turn on the one I want to access?

No. FireWire enclosures pass through bus power, but not signal. The only
one I ever found that did was a Sony CD-RW drive. If you don't use a hub
(or a host adapter with multiple ports), you'll have to turn on all the
devices in the daisychain between the one you want to use and the host
computer. You can unmount the other disks, but the enclosures will have
to be powered.
 
R

Rod Speed

Oldspook said:
I have one WD 250GB external hard drive connected by firewire. It
performs well and is very fast for an external drive. I turn the drive
off when I don't need to access its data.
I plan on buying 2 more of the same drive and connected them daisy
chained to the firewire. With 3 drives daisy chained will I be able
to keep the drives off and only turn on the one I want to access?

Nope, you'll need a firewire hub to do that.
 
B

Beemer Biker

Oldspook said:
I have one WD 250GB external hard drive connected by firewire. It performs
well and is very fast for an external drive. I turn the drive off when I
don't need to access its data.

I plan on buying 2 more of the same drive and connected them daisy chained
to the firewire. With 3 drives daisy chained will I be able to keep the
drives off and only turn on the one I want to access?

Sorry: You need to maintain power on all.

Be aware that some chipsets do not properly handle a bus reset when daisy
chained. You might want to look at this blog
http://www.bustrace.com/delayedwrite/index.htm and search for the word
"chain". All this applies to windows (xp or 2k). I consistently got
corrupted disks when the slowest device was not at the end of the chain. A
firmware update for prolific chipset made the problem managable. Even with
the firmware upgrade I get errors on 2K and I avoid daisy chaining entirely
on win2k. Invest in a disk recovery program if you want to keep critical
stuff on external drives and you dont have backups.

We have seen the problem show up even on linux as a "reset storm" where
one device comes up before the rest do and gets reset a 2nd time. This shows
about 100 dual amd servers all daisychained with firewire:
http://tinyurl.com/5uhd9


--
=======================================================================
Beemer Biker (e-mail address removed)
http://TipsForTheComputingImpaired.com
http://ResearchRiders.org Ask about my 99'R1100RT
=======================================================================
 
O

Oldspook

Beemer Biker said:
Sorry: You need to maintain power on all.

Be aware that some chipsets do not properly handle a bus reset when daisy
chained. You might want to look at this blog
http://www.bustrace.com/delayedwrite/index.htm and search for the word
"chain". All this applies to windows (xp or 2k). I consistently got
corrupted disks when the slowest device was not at the end of the chain.
A
firmware update for prolific chipset made the problem managable. Even
with
the firmware upgrade I get errors on 2K and I avoid daisy chaining
entirely
on win2k. Invest in a disk recovery program if you want to keep critical
stuff on external drives and you dont have backups.

We have seen the problem show up even on linux as a "reset storm" where
one device comes up before the rest do and gets reset a 2nd time. This
shows
about 100 dual amd servers all daisychained with firewire:
http://tinyurl.com/5uhd9

I use windows XP Pro. The 1394 is on the motherboard, Asus P4C800-E. Would a
firewire hub solve the corruption problem?
 
E

Eric Gisin

It depends on the powering of the enclosure.
The PHY chip transfers data between the ports,
and is powered by cable, external, or either one.

A 3.5/5" enclosure would be externally powered and would not.
A 2.5" enclosure could be any configuration. Cable powered would work.
 
J

Jonny

Oldspook said:
I use windows XP Pro. The 1394 is on the motherboard, Asus P4C800-E. Would
a firewire hub solve the corruption problem?

Total length of a firewire cable, including chaining, is very minimal.
Instead of reinventing the wheel, just use another firewire port.
 
F

Folkert Rienstra

Eric Gisin said:
It depends on the powering of the enclosure.

You just wait a little and someone comes to put the babblebots to shame.
Obviously Rodbot just shamelessly copied Neill's response.
The PHY chip transfers data between the ports,
and is powered by cable, external, or either one.
A 3.5/5" enclosure would be externally powered and would not.

Not necessarily.
Just like with SCSI and SCSI terminators the PHY logic could stil be
powered by the cable (or even a standby power circuit that is sepera-
ted from the power switch) and the power switch just powers the HD.
Whether that works or is implemented may depend on chipset and mfgr.
A 2.5" enclosure could be any configuration. Cable powered would work.

That would depend on whether it can be powered off at all or what gets
powered off and what not.
 
N

Neill Massello

Eric Gisin said:
It depends on the powering of the enclosure.
The PHY chip transfers data between the ports,
and is powered by cable, external, or either one.

A 3.5/5" enclosure would be externally powered and would not.
A 2.5" enclosure could be any configuration. Cable powered would work.

The power switch on a FireWire enclosure usually controls everything
except the pass-through of FireWire bus power. When the switch is off,
_all_ the elctronics in the enclosure are dead. This also holds for most
2.5 inch enclosures. Obviously, an unswitched 2.5 inch enclosure's chip
will be on whenever it's getting bus power; but then so would its drive,
and that's not what the OP seems to have in mind.
 
F

Folkert Rienstra

Neill Massello said:
The power switch on a FireWire enclosure usually controls everything
except the pass-through of FireWire bus power.

What's the bloody point if you need the electronics of this device
to work for devices down the road to be able to function at all.
When the switch is off, _all_ the elctronics in the enclosure are dead.

That's what you say..
 
O

Odie Ferrous

Folkert said:
What's the bloody point if you need the electronics of this device
to work for devices down the road to be able to function at all.


That's what you say..


Hey, Folkert!

I really missed you the last couple of days.

I thought you may have had an argument with the underside of a bus or
something.

Obviously not.

Pity.

Never mind - I won the lottery last night, so I can deal with it.


Odie
 
F

Folkert Rienstra

Odie Ferrous said:
Hey, Folkert!

I really missed you the last couple of days.

I thought you may have had an argument with the underside of a bus or
something.

Obviously not.

Pity.

Never mind - I won the lottery last night, so I can deal with it.


Odie
--
Retrodata
www.retrodata.co.uk
Globally Local Data Recovery Experts

I see you forgot to add your signature, I amended that for you.
Can't have you going out of business, can't we.
 

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