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Hard Drives and my quest to be a tech geek

Terry

Terry

New member
OK here is the question:

Let's assume I just bought an external hard drive: 100gb 7200 that can be hooked up as eSata, FireWire 800, FireWire 400 or USB 2.0

How big a difference is there between running the drive off the different connections?

If there is a big difference, and you don't have the fastest port, then is it worth buying the fastest drive?
 
Robert Campbell

Robert Campbell

Well-known member
This seems a very modest drive.
I understood - I may be wrong - that eSATA isn't hot swappable, so it must be on all the time.
I have a drive which can be connected by USB [2] or FW [400] and it seemed much quicker on FW.
It isn't difficult to run out of USB ports - FW seems to have the advantage here.
I also gathered that the limiting factor is the speed of the drive itself.
 
Terry

Terry

New member
That one is the modest "travel" drive. The others are 1TB.

That is sort of the question, what hits the limit... So, for instance on USB 2.0 would you get the same performance from a 5200 and a 7200 drive? But on FireWire 800 you will see the difference in drive speed between the two?
 
Robert Campbell

Robert Campbell

Well-known member
TEBnewyork said:
That one is the modest "travel" drive. The others are 1TB.

That is sort of the question, what hits the limit... So, for instance on USB 2.0 would you get the same performance from a 5200 and a 7200 drive? But on FireWire 800 you will see the difference in drive speed between the two?
Click to expand...
Get a USB 'travel drive' - you don't need any extra power source.
For a PC reformat from FAT32 to NTFS - I know nothing about Macs

Otherwise, I must pass...sorry!
 
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Terry

Terry

New member
Robert Campbell said:
Get a USB 'travel drive' - you don't need any extra power source.
For a PC reformat from FAT32 to NTFS - I know nothing about Macs

Otherwise, I must pass...sorry!
Click to expand...

Thanks,
I'm on Mac.

Actually, I can also run FireWire without power as well. I am changing around a lot of system stuff all at once and have some new drives and old drives so I really just want to get the right parings and make sure I understand what limits what.

terry
 
ChrisDauer

ChrisDauer

Workshop Member
# USB2 = USB 2.0 port rated at 48MB/s
# 1394a FW400 = FireWire 400 port rated at up to 40MB/s
# 1394b FW800 = FireWire 800 port rated at up to 80MB/s
# SATA = SATA port rated at up to 150MB/s
# SATA2 = SATA II port rated at up to 300MB/s

So, in theory, your drive should be able to do up to 300 MB/s.

Pick which one works best for your needs and go from there.

Personally, I run USB 1.0 and 2.0. 2.0 is 'okay', but when I'm accessing stuff via eSata, I'm in heaven. It's like the external drive is an internal drive, it's so fast. I do this because I've only got a single fire-wire cable, but tons of USB cables. YMMV.
 
Bob

Bob

Administrator
Staff member
Well, you can't get it off the drive any faster than the platter rotates. Also it depends a lot on how you use it. I will assume that you are reading sequentially very large files (this is an optimistic assumption, since other usage modes will be slower)
Assuming that it performs like a seagate 7200.2, then the maximum sustained transfer rate (sequential multi sector reads) is 59.0 MB/sec. That is rarely achieved because it requires that disk requests come in in just the right order and at the right time to reduce latency. More usual field experience might be somewhere about half of this.
At USB2.0 rates, you will not be bottlenecking this drive so as long as you are at USB 2.0 or better, it won't make a difference.
Compare this to say the seagate 7200.11 drive which transfers at 105MB per sec sustained actually might be bumping up a little on the USB2.0 rates, and thus might benefit from Firewire 800.
I have measured eSATA and firewire 800 disk performance and found it to be more a function of the driver than the interface. I have a specific pc (a Toshiba) that transfers twice as fast across firewire 400 than my macbook pro, which is usually about twice as fast as most windows boxes (go figure). The main reason that most operating systems work better in eSATA is that 1) it is the native direct interface for internal disks and 2) It is a point to point interface which does not require arbitration to select a particular device. I would not be surprised to find the arbitration delays to be the major bottleneck in all USB and Firewire implementations and not the actual transfer rate. Bottom line, with that particular drive you will not be able to observe much difference between any of the "bus" type interfaces (USB2.0, Firewire 400 or 800) but might see a little difference in eSATA, but probably not enough to make a real difference.
Now if you had a seagate Cheetah 15k.5 drive, which spins over twice as fast, it can sustain a transfer at up to 125 MB per sec even though its physical interface (4Gb Fibre channel) can support about 400GB/sec.
Oh, folks might say "what about the cache in the drive...", well all that usually does is get your sector by sector read commands (as they come from the OS) begin to approximate the off-the-platter sustained read speed since the drive will fill the buffer (usually) with a full track of data even though a single sector might be currently at the head of the queue. It is far better to have it in a buffer than to suffer what might be nearly a full latency (time it takes the platter to come all the way around) before the next sequential sector comes under the heads again since probably the OS didn't quite make it in the inter sector gap. Note that even though buffered, the bits don't come off the platter any faster, you need that buffer to smooth out the synchronization delays between os, interface, seeks, and platters.
One interesting example of how this really applies in practice is that the Lacie "BigDisk" (I think that is what is called) is formatted with a striped raid, so that there are two drives supplying data in parallel to the interface. They did this in order to take advantage of the firewire 800 interface. A single non-semiconductor drive cannot provide it data as fast as it can eat it today.
Now if you are talking a raid controller card such as what is offered for the MacPro, then it has the capability of transferring from up to four drives in parallel over independent sata channels. Now that is now to take advantage of SATA!
-bob
 
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Maggie O

Maggie O

Active member
Ah, I thought that might be the case.

I just bought two OWC Mercury Elite Classic 500GB FW 800 drives, myself.
 
Terry

Terry

New member
Bob,
I'll say thanks right now but I am only on my third read through and it is going to take me some time to digest all that you have written. I'll probably be back with some more simpleton questions soon....

terry
 
ChrisDauer

ChrisDauer

Workshop Member
Bob said:
[SNIP] :lecture: [SNIP]
-bob
Click to expand...
Or what Bob said! :bugeyes:

FWIW, some online techy site (Tom's Hardware, Anatech, PC Extreme, or one of them) did a test between a striped Raid versus a mirrored raid to see performance differences. It was shockingly and appallingly small. Like 2-3% improvement for a pair of 7.2k spin drives. Going to a single 15k drive was significantly better than a striped raid. For multiple reasons (lose a single drive and lose all data (integrity). I'll see if I can find the info but I'm dash out the door right now to meet up for dinner.
 
M

meilicke

Guest
I tested the same drive over a FW400 and FW800 interface on my MacPro, and found FW800 was 15% faster. I used IOMeter to test, with a typical file server load (80% read, 20% write, 100% random hard drive head seeks, lots of different block sizes), as defined by Intel. As was said earlier, a lot depends on the drive as well.

That said, I have all of my images on an external USB drive at home, and just the Aperture catalog on my internal drive, and the speed is fine.

It all boils down to what you need, and how fast is fast enough?

-Scott
 
M

meilicke

Guest
If there is a big difference, and you don't have the fastest port, then is it worth buying the fastest drive?
Click to expand...
I forgot - it was said earlier, but a faster drive will help on USB all the way to eSATA. The drive head will rotate faster, and you will, at the very least, get to your files faster.
 
Jack

Jack

Sr. Administrator
Staff member
Here is the bottom line...

SATA speeds refer to maximum BURST rates in BITS (b) per second, NOT BYTES (B) per second. So, SATA2 runs at maximum BURST at 3 Gb/s, or about 300 MB/s. SUSTAINED read and write, like what we do with images, is MUCH slower even on SATA2 drives.

My BEST SATA2 drives are capable of just over 100MB/s on SUSTAINED read or write tapering off to 70MB/s or so toward the slow end of the drive, so FW800 at 80 MB/s is for all practical matters pretty darn close... SATA1 drives only ran at about 50 MB/s to begin with, so not even significantly faster than USB2 or FW400... Fortunately, SATA2 drives are twice as fast. BTW, this is why you need to remove the jumper on Seagate SATA2 drives, as they default to SATA1 speeds if the jumper is left on :)

The other problem with eSATA is it is NOT hot-swappable or hot-bootable. Hence, the only time I would say it makes a difference on an EXTERNAL drive, is on a desktop where it's permanently connected via eSATA, or for when you want to transfer more than a couple hundred GB and have limited time on a laptop. Otherwise it is not worth having to shut the computer off, connecting eSATA and rebooting to run it. By contrast, the convenience of plug&play FW800 is a breeze on a laptop or a desktop for transferring even a few hundred Gigs of images...

These are the reasons I didn't recommend the eSATA version portable drive box for your laptop: I didn't feel it was worth the cost difference to gain a function you probably would only rarely or never use with your laptop. However, I feel the opposite is true for a desktop: I have my desktop external drives connected by eSATA since I don't need to disconnect them and use them just like internals, so the lightening fast burst and faster sustained R/W is welcome.
 
C

cmb_

Subscriber & Workshop Member
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?
 
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Terry

Terry

New member
I confess there was a dirty little secret built into my question. I was back to thinking about the MacBook Air as the only time I need Photoshop on a laptop is at a workshop and normally would do that type of work on my desktop. With the addition of RAM and a big Firewire 800 SATA2 for the desktop I'm feeling pretty good (or will tonight when I figure out what the jumper is and install the new drive - which arrived).
On a MBP, I also understand what a good setup would be. I was trying to figure out if I would want to shoot myself being limited to USB2.

Now, I have a much better grasp on the detail which makes my brain happier!


Jack Flesher said:
Here is the bottom line...

SATA speeds refer to maximum BURST rates in BITS (b) per second, NOT BYTES (B) per second. So, SATA2 runs at maximum BURST at 3 Gb/s, or about 300 MB/s. SUSTAINED read and write, like what we do with images, is MUCH slower even on SATA2 drives.

My BEST SATA2 drives are capable of just over 100MB/s on SUSTAINED read or write tapering off to 70MB/s or so toward the slow end of the drive, so FW800 at 80 MB/s is for all practical matters pretty darn close... SATA1 drives only ran at about 50 MB/s to begin with, so not even significantly faster than USB2 or FW400... Fortunately, SATA2 drives are twice as fast. BTW, this is why you need to remove the jumper on Seagate SATA2 drives, as they default to SATA1 speeds if the jumper is left on :)

The other problem with eSATA is it is NOT hot-swappable or hot-bootable. Hence, the only time I would say it makes a difference on an EXTERNAL drive, is on a desktop where it's permanently connected via eSATA, or for when you want to transfer more than a couple hundred GB and have limited time on a laptop. Otherwise it is not worth having to shut the computer off, connecting eSATA and rebooting to run it. By contrast, the convenience of plug&play FW800 is a breeze on a laptop or a desktop for transferring even a few hundred Gigs of images...

These are the reasons I didn't recommend the eSATA version portable drive box for your laptop: I didn't feel it was worth the cost difference to gain a function you probably would only rarely or never use with your laptop. However, I feel the opposite is true for a desktop: I have my desktop external drives connected by eSATA since I don't need to disconnect them and use them just like internals, so the lightening fast burst and faster sustained R/W is welcome.
Click to expand...
 
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