Hard Drives and my quest to be a tech geek

[Jack]

Jack - if you wanted to use an external drive as a scratch disk for a laptop when traveling would you then recommend eSATA over Firewire 800 - or not bother at all?

Unfortunately, the answer here isn't as simple...

The biggest issue with eSATA on a laptop is it is NOT a direct SATA connection to the MB, but rather goes through via the smart-card I/O port. Depending on the adapter and your system, the net transfer speeds may not be any faster than SATA1 and may in fact not even be that fast, meaning you'd be better off using FW800 or possibly even USB2/FW400(!) OTOH, if your system allows a flow though at true SATA2 speeds, then the combined burst and sustained rates will give eSATA a notable advantage even over FW800 on a scratch drive.

If one feels the need for a true scratch disk on a laptop, I would suggest the techiest move would be to remove the internal DVD drive and replace it with a second laptop drive. Also probably best if that DVD drive is also SATA2 since IDE is slower enough that FW800 may be as good...

Frankly, this is where we get to the point that a dedicated desktop delivers superior performance for digital imaging. A laptop has limited I/O bus speeds, limited RAM capacity and RAM bus, and does not generally support additional drives as conveniently. In addition, the biggest performance upgrade will be achieved with a direct-to-MB RAID array, again not supported very well in laptops...

At the end of the day, this is why I don't generally worry about scratching on when on my laptop, and moreover, tend to work in 8-bit mode: I know I'm going to re-work my serious images on my big machine before printing or delivering to a client anyway.

However, One thing I've considered is a really fast, larger capacity SD card might make a respectable scratch drive if connected via a fast smart-card reader/writer Don't know how well it will work, but need to pony up for a fast 16G card and try it...

 

[Robert Campbell]

That would be feminine wiles, Robert. Not all females are wily.

I stand corrected: but it reminds me of Mrs Margaret Thatcher, one time Prime Minister, whose deputy was Mr William Whitelaw. Mrs Thatcher is supposed to have said that 'every Prime Minister needs a Willie'.

 

[MrSlezak]

There a few different things that effect this;

Drive speed (when using a single 7200 rpm drive and something other than RAID)
---
USB -- 7200 is fine, USB is way slow
1394a -- 7200 is fine, 1394 is a touch quicker than USB, but won’t tax a 7200 drive
1394b -- Here 7200 starts to show it’s limits, 1394b as indicated earlier does cap out at 80MB/s for S800. At S800 you should get about
60MB/s for writing
70MB/s for reading
eSATA -- 7200 drives are a bottle neck on eSTAT and I haven’t see a boxed product that ships with an 10,000rpm drive yet

Bridge Controller
--
The bridge controller in the drive enclosure will effect the perf on the case. There are only a few companies that make storage bridges (InitI|O, Oxford Semiconductor, Prolific, etc…) and everyone else sells them in their case/product (be it LaCie Seagate, Western Digital, etc…). To my knowledge there is only one company that provides a ‘quad’ board – Oxford Semiconductor. In my experience, the chipsets that Oxford sells are great, but you need to watch the firmware rev to make sure you’re getting max perf. across all busses on the bridge.

Non-obvious
--
CPU hit during transfers -- CPU impact varies wildly between BUS’. HDTune (http://HDTune.com ) is a util for PCs – they have freeware and ~$45 versions – that will show you the CPU hits range somewhat like this:

eSATA ~ 10%
1394a ~ 15%
1394b ~ 30%
USB ~ 35%

with the same drive in a multi bridged enclosure running the same test on the same drive just changing the connection to the computer.

At some point in the future, we might see Mutli-Core systems help off load some of the impact to CPU hits, but given Intel drives USB specs, and sells processors I could see USB CPU usage continuing to be high into the USB 3.0 range. 1394 is designed to share the transfer speeds between controllers and devices.

Power Supply -- The power supply will effect speeds on these as well. When you are using these devices for travel, you should try to make sure you carry the actual wall wart that comes with your product and avoid using USB bus power. USB bus power is horribly taxing to battery life on a laptop that isn’t plugged in, and if you are using fast drives they will be thirsty. 1394a / 1394b both provide bus power provided the host controllers are powered correctly (e.g. 1394a ‘four pin’ adapters do not provide power). I can’t recall if eSATA does now, or will soon support power. And anything running over an ExpressCard or PCCard / PCMCIA adapter will be limited as to how much, if any, power will show up on that adapter.

To Jack's thinking about as SD slot/card for swap – the reader in most laptops these days is attached via USB and it is an interesting trade off to put swap on the system if it impacts CPU. If you are using a 1394 based reader that’s ok and I haven’t seen a SATA/eSATA one yet.

 

[Jack]

To Jack's thinking about as SD slot/card for swap – the reader in most laptops these days is attached via USB and it is an interesting trade off to put swap on the system if it impacts CPU. If you are using a 1394 based reader that’s ok and I haven’t seen a SATA/eSATA one yet.

I'm actually suggesting trying it through the express card port, which is pretty fast -- 5Gb/s I think? Anyway, lots faster than usb2, FW400 and FW800... Using it, a good reader/writer and a fast 16 GB SD card might be interesting.

Cheers,

 

[MrSlezak]

Ah, ExpressCard might not be a bad route to take for swapping... That I hadn't considered (keep forgetting there are ExpressCard devices out there... )