I've just installed a 3TB drive (single partition) in my home PC, copying stuff back to it (12000 podcasts 15-30mb each) from a USB drive is really slow and jerky. I had to leave the copy running this morning as I left for work as it was taking so long, you might get a file or two copying in what I would say is normal time and then it might get stuck on a file for a minute or so before doing anything at all.

The PC is running Windows 7 professional and has 3GB ram.

Any ideas?

Is the external drive a unit you've bought completely as-is (like a WD Mybook), or did you buy the 3TB drive separately and put it in an old external enclosure yourself?
I had this also happen to me, in a case where the old external enclosure didn't function well with more recent, big drives. You can get the strangest results that way. That may be a reason. Maybe the enclosure's chipset doesn't get along with GPT formatting or something.

Otherwise, maybe a dodgy cable?

Forgot the model number, it's WD30EZRX

Just to be clear, the 3TB drive is internal in the PC, I'm writing to it from an external 1TB USB drive.

Ah, sorry, I misunderstood.

Copying to/from usb 2.0 is pretty slow. About 25 MB/s is considered 'normal speed' Do you reach that speed?

I don't think so, had to leave for work, certainly seemed a lot slower than it used to be writing to the 1TB disk it replaced. Apart from speed the other noticeable factor was that it was happening in bursts.

Can't you remove the external drive from it's enclosure and also hook it up to a SATA port? That way you would be able to use it at full speed, which would easily be 3-4 times faster than with USB 2.0. I know it's a hassle, but when copying such a large amount of data, it's probably worth it.

Of course, that would not give you the reason why your USB drive acts up...

No, not unless I leave the side of the PC off, it's only got 2 drive bays, both are filled.

Are the partitions aligned to 4KB boundaries? If not, performance can be poor.

OK, how do I check/change the boundaries?

You'd need to repartition the drive. But if you've paritioned it with Win7, then it should be OK. Win7 automatically sets it up correctly.

I partitioned it with Win7

Then that won't be the problem.
Are you connecting it directly to the PC? Not via a USB hub? Are there other devices connected via USB to the PC? On the same hub? Try removing all other USB devices. Remove everything with the exception of the external drive and maybe a keyboard/mouse combo. Then make sure there's nothing else connected to the the hub the disk is connected to (nothing else connected below or above the USB connector where the disk is connected to), not even the keyboard or mouse.

PS2 Mouse/keyboard. USB HDD plugged directly into PC no other USB devices attacched

Recommend checking:

- Computer System's BIOS configuration for the large drive. There may be a few different settings there that affect the drive's performance. For instance, I have a computer here at work where I have to disable the "SATA BIOS ROM" feature in order to get the system to boot from the CD-ROM, but it makes the hard drives dog-slow. So I re-enable that feature in the BIOS after I'm done with whatever I needed the CD-ROM booting for.

- Make sure you have the latest Windows OS device drivers updated for the motherboard, SATA controller, PCI chipset, and perhaps even the drive itself.

- Rule out the external USB drive as a factor. Copy (not move) a single very large file to another location on the same 3TB hard disk. Is that really slow, too, or is it lightning fast? If so, then I would guess the problem is the external drive and/or its enclosure, not the 3TB drive.

Thanks Tony will try all the above. I had to fiddle with the BIOS to get the drive seen to start with (Drive 1 = off)

From the other posts here, I think some people may have missed this point.

Yes, sorry. Anyway I got home last night and the copy had hung, couldn't get windows to shut down or restart. BIOS wasn't seeing the 3 TB drive. I didn't have another cable to hand so I switched ports on the m/b, it came up in BIOS and now works fine.

No idea what's going on as I'd already copied my music files (35000ish) the same way with no issues. It's a brand new Acer PC, I've never had a port on a m/b fail before, but could that be it?

I'll see if I can find another SATA cable at work, but like I say it's working fine in the other port.

It's not sure the port is pooched. Maybe there was a bit of dust between the connector and the cable. These things are delicate and it doesn't take much for them to malfunction.
It's entirely possible that if you put the cable back onto the previous port it'll work again.

That said, maybe the new port is a sata600 port instead of a sata300 port? While this is no reason in itself as to why it failed (since sata 600 and sata300 are backwards compatible), your disk *is* a sata600 model so you could just as well connect it to the best port available.

The PC has it's SATA ports in 2 locations (BIOS and physically) 1 & 2 are the Boot HDD and DVD, the new HDD was on 5 and is now on 6. I'd guess they're both the same type of port.

Some motherboards have two SATA controllers -- the one built in to the chipset might only support 4 ports, so the motherboard manufacturer will wedge another SATA controller on there for extra ports.

It's possible that, by moving to a different port, you moved to a different controller.

I don't think there's anything in BIOS that says how many controllers there are, I might take a look later.

On recent motherboards, maximum 6 SATA ports are directly connected to the chipset of the motherboard. (viewable in the bios/EFI) Usually no more than 2 of those are SATA600, the other 4 are SATA 300. Most of the times they are color-coded so you can distinguish them from each other. If not, you should be able to read from the motherboard pcb which ones are which.

If you have more than 6 SATA ports on your motherboard, this means these are driven by an external chipset. While these should work too, I've known them to cause issues on many occasions, so I always try to avoid them. I advise you to do the same.

Which chipset does your motherboard use?

The bios won't show you any info on other controllers. It'll only be able to control the drives directly connected to sata ports on the chipset.
External controllers use their own chipset and hence their own drivers. The bios is unaware of them. As said, I've known those to give some very strange results, so I would avoid them.

BIOS only shows 4 ports; 1, 2, 5, 6. That's all I could see in there but it was dark, I'll check if it says anywhere which are 600.

I'll check. Maybe I should have stuck with my original plan to rebuild one of my old DIY machines...

I can attest to that.

I have an external drive in a Vantec enclosure that can connect either by eSATA or by USB. If I run it through eSATA it is very fast, about 10x the speed of the USB connection. For a while.

Then I get the same symptons that tahir has--it copies a couple files, pauses for as much as a minute, then a couple more, and finally locks up the system so hard that I have to pull the power to do a reboot.

I've tried a different Vantec dock, a different cable, anything else I could think of, nothing works, so I just use the USB connection. It's a 2TB drive backing up an internal 2TB drive that is now so full (96%) of unchanging data that even through USB backups are now a matter of a few minutes, so I just leave things as they are. No sense going around asking for trouble, right?

tanstaafl.

The BIOS might have a setting to enable/disable the extra controller. If it's enabled, you'll probably see something in the POST check at startup.