Thinkpads Forum

I could not find a t60 dock with SATA, although the t40 series had SATA in their docks --- what gives? How are you guys hooking up your external drives?

I bought an external USB SATA adapter and use that for my SATA external drives.

that destroys the bandwidth of the SATA bus -- you're better off buying an expresscard SATA card, they range from 17-40$ and give you the full 3.0Gb/s vs USB 2.0's 480Mb bursting. (a huge speed boost)

That is a pointless comparison.

Modern hard drives (even the 10,000 RPM desktop Raptors) don't come CLOSE pulling data off the drive at 150MB/s, much less 3GB/s.

Even the fastest laptop drives can't pull data off the platter more than about 60-70MB/s. That's 1/8 the bandwidth of a USB2.0 port.

Copy a 5-10GB file disk to disk via the internal SATA and Ultrabay adapter (both of which are on the INTERNAL HD Controller) and then try the same thing (with an identical drive) with the external USB 2.0 adapter and the internal drive.

The transfers will be within SECONDS of each other.


And don't give me the old argument about BURST transfer rates. Do you know how long it takes to clear out the cache RAM from a HD during a burst transfer? MILLISECONDS. From then on you are limited by the platter transfer rate.

brentpresley wrote:That is a pointless comparison.

Modern hard drives (even the 10,000 RPM desktop Raptors) don't come CLOSE pulling data off the drive at 150MB/s, much less 3GB/s.

Even the fastest laptop drives can't pull data off the platter more than about 60-70MB/s. That's 1/8 the bandwidth of a USB2.0 port.

Copy a 5-10GB file disk to disk via the internal SATA and Ultrabay adapter (both of which are on the INTERNAL HD Controller) and then try the same thing (with an identical drive) with the external USB 2.0 adapter and the internal drive.

I think you may be equating Gb = GB. SATA II has a maximum transfer rate of 3Gb/s (Gigabits - not bytes) = 384 MB/s. USB2 has a maximum transfer rate of 480Mb/s = 60MB/s.

Now, for example, the Hitachi 7200 RPM 100GB laptop harddrives are spec'd at having a media transfer rate of 629Mb/s = 78.625MB/s.

So, in fact, todays laptop HDs can most certainly exceed the throughput of USB2 for a sustained transfer.

However, I will say that it is likely a user would notice little difference between the two, unless they consistently did large file transfers.

SATA uses 8b/10b encoding, so 3Gbit/sec translates to 300MBytes/sec. (Divide by 10, not by 8.)

tpribors wrote:SATA uses 8b/10b encoding, so 3Gbit/sec translates to 300MBytes/sec. (Divide by 10, not by 8.)

You are right. Forgot about that in my haste....

brentpresley wrote:That is a pointless comparison.

Modern hard drives (even the 10,000 RPM desktop Raptors) don't come CLOSE pulling data off the drive at 150MB/s, much less 3GB/s.

Even the fastest laptop drives can't pull data off the platter more than about 60-70MB/s. That's 1/8 the bandwidth of a USB2.0 port.

Copy a 5-10GB file disk to disk via the internal SATA and Ultrabay adapter (both of which are on the INTERNAL HD Controller) and then try the same thing (with an identical drive) with the external USB 2.0 adapter and the internal drive.

The transfers will be within SECONDS of each other.


And don't give me the old argument about BURST transfer rates. Do you know how long it takes to clear out the cache RAM from a HD during a burst transfer? MILLISECONDS. From then on you are limited by the platter transfer rate.

On my server I can't notice a difference when making a backup via SATA card or USB2.0

how many people use your server? lol. if its just you, then sure.

brentpresley wrote: Even the fastest laptop drives can't pull data off the platter more than about 60-70MB/s. That's 1/8 the bandwidth of a USB2.0 port.

Ok, sir you are mistaken. There is DEFINITELY a discernable difference between USB buses and SATA buses when it comes to utilizing the maximum transfer rates of hard drives. USB 2.0 has a maximum of 480 Mbps <-Mega bits, not mega bytes. Thus it saturates at 60 MB/s at its very MAX. Since you just said that some drives are capable of pulling data off a drive at 60-70 MB/s, then you will clearly run into a bottleneck over the USB bus. This is of course ignoring that you can have other devices on the same USB bus that will steal bandwidth away. Thus there is a clear need for a dedicated SATA or PCI express bus to gain maximum performance.

kulivontot wrote:

brentpresley wrote: Even the fastest laptop drives can't pull data off the platter more than about 60-70MB/s. That's 1/8 the bandwidth of a USB2.0 port.

Ok, sir you are mistaken. There is DEFINITELY a discernable difference between USB buses and SATA buses when it comes to utilizing the maximum transfer rates of hard drives. USB 2.0 has a maximum of 480 Mbps <-Mega bits, not mega bytes. Thus it saturates at 60 MB/s at its very MAX. Since you just said that some drives are capable of pulling data off a drive at 60-70 MB/s, then you will clearly run into a bottleneck over the USB bus. This is of course ignoring that you can have other devices on the same USB bus that will steal bandwidth away. Thus there is a clear need for a dedicated SATA or PCI express bus to gain maximum performance.

here here! i was too lazy to type that haha.

USB 2.0 does definitely max out before a modern 7200 rpm drive does -- though the difference really only shows on sustained sequential reads (ie large files on an unfragmented disk). On an external 5400 rpm drive the difference would likely be inconsequential.

Firewire will be somewhat faster than USB2, but eSATA is likely optimal for performance (unless you want to go SAS, but I suspect that'll be overkill for a ThinkPad).

See some benchmarks in this thread:
http://forum.thinkpads.com/viewtopic.php?t=29346

I have been looking at the issues of sATA and USB-2 external hard disk drives for some time. See this forum topic http://forum.thinkpads.com/viewtopic.ph ... hard+drive

Here are results of two simple tests I performed (included in the forum )

I bought a PC Express card (http://www.siig.com/product.asp?catid=7&pid=1036) and successfully set it up on my TP T60p. I have the external Seagate 500 GB eSATA disk drive attached and running.

This new set up has resulted in these (admittedly unscientific) results.

A 10.5 GB file transfered from the T60p HDD to the Seagate 500 GB eSATA external drive in 9 minutes and 4 seconds.

The same 10.5 GB file transfered from the T60p to a Seagate 500 GB USB 2 external drive in 18 minutes and 12 seconds.

I transfered another big file (folder) from my T60p to both a Seagate SATA 500GB hard disk drive and a Seagate USB 2 500 GB hard disk drive. the results are pretty much the same as before.

the folder is 14.6 GB (5578 flies, 532 folders)

T60p to Sata HDD.......10:35
T60p to USB 2 HDD......20:54