Usb hard drive - slow write speed

Hey all you mac savvy people out in mac land.
I got the airport extreme n edition for christmas and I set the thing up at the 5Ghz N speed (300Mbps) and all is happy. then I connected my external usb 2.0 hard drive to begin using that as a network storage, the airport picks it up and sees it, and I can read/write to it. When I read from it, it reads really fast at about 6 MBps (i can see this speed by using the iStat widget) but the write speed to it is about 2 MBps (again, through iStat). I know that the hard drive itself is not slow because hard wired to it is really fast and i know that the airport extreme is fast for transfers because i transfer about 12-13 MBps to my pc. Why is it that the write speed going wireless to it is slow? any ideas?

hi Daew,
Welcome to the Lenovo Forums.
The results that you got while running CrystalDiskMark is normal. The SATA 2 (3Gb/s) that you mentioned is actually the SATA interface support, not the actual read/write performance.
If you have a Seagate HDD (eg. ST10000LM024), check these specs
From the above specs, the unit has a cache that has a read/write max speed of 145 MB/s but there are environmental factors and power requirements to get this speed (eg. read/write speed on AC power is differente from battery power).
AFAIK, if this is the specs that is design for this drive, there's no way to speed it up.
If you're planning to upgrade in the future though, you can get an SSD for faster read/write.
Regards
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Similar Messages

G710 hard drive read/write speed

Hello,
I have a brand new Ideapad G710 with 1TB Serial ATA 2, 5400rpm with advertised speed of 3 Gb/s (= 384MB/s).
I am running Windows 7 ultimate x64 with SP1.
When I test hard drive read/write speed (I used CrystalDiskMark) I get results of about 100MB/s, which is 3-4 times slower than it should be.
I am not running any resource heavy applications (Resource monitor reports Disk I/O to be 0 most of the time in idle state). I have 3 partitions, each with 16-32GB paging file size and all are >90% empty. All partitions have been defragmented before testing.
Is this normal? Are there any lenovo drivers or utilities than I might be missing or that can slow/speed this?
Solved!
Go to Solution.

hi Daew,
Welcome to the Lenovo Forums.
The results that you got while running CrystalDiskMark is normal. The SATA 2 (3Gb/s) that you mentioned is actually the SATA interface support, not the actual read/write performance.
If you have a Seagate HDD (eg. ST10000LM024), check these specs
From the above specs, the unit has a cache that has a read/write max speed of 145 MB/s but there are environmental factors and power requirements to get this speed (eg. read/write speed on AC power is differente from battery power).
AFAIK, if this is the specs that is design for this drive, there's no way to speed it up.
If you're planning to upgrade in the future though, you can get an SSD for faster read/write.
Regards
Did someone help you today? Press the star on the left to thank them with a Kudo!
If you find a post helpful and it answers your question, please mark it as an "Accepted Solution"! This will help the rest of the Community with similar issues identify the verified solution and benefit from it.
Follow @LenovoForums on Twitter!

Hard drive read write speeds are too slow

I was having an issue with 17inch macbook pro. was getting 4.0mb/s read write speed tops. and smart status failure.
So i replaced the drive. The new drive is a 7200 RPM 500GB WD drive. I'm getting 12.0mb/s on top speed. Computer feels a little quicker but still slow overall.
I ran this test on a fresh install of snow leopard.
Is it just me or do those read/write speeds on the new drive still seem slow?
2007 17inch macbook pro with 2gigs of ram.

That does seem slow - on the other hand, what are you using to measure it?
My 1Tb 2.5" SATA drive performance shows as follows: http://grab.by/7zau
Xbench Stats: http://grab.by/7zau
Anything in System Profiler? http://grab.by/7zaR
Link Speed at 3 Gb?

Read/Write speeds with Airport Extreme and USB Hard Drives

Anybody know how fast the read/write speeds are with a USB hard drive and the Airport Extreme Base Station?
My Setup
I have a 17 MBP (2010) and a 13 MBP (2011) - no SSD's
MBP generally connect via 802.11n 5Ghz with a very strong signal
Gigabit connection on a Windows Desktop
I have a variety of external drives (7200, 5400, Drobo) at varying capacity (320GB, 2TB, 5.6TB)
Goals
Backup: Time machine
Backup: File copies of pictures and home videos (greater than 1GB files)
Backup: Crashplan
File sharing: Aperture libraries--not sure if that is possible or practical. That is something that I need to research further...but on the off chance people have experience with it.
Thanks!

ishjen wrote:
Anybody know how fast the read/write speeds are with a USB hard drive and the Airport Extreme Base Station?
Welcome to Apple's discussion groups.
Apple's AirPort base stations aren't known for fast file serving, but for most purposed they're fast enough.
I can't comment specifically on your Aperture plan, but with some software it's important to avoid simultaneous access by more than one user.

Slow transfer speed to external USB hard drive

I'm not sure if this forum is the right fit, but here goes. I'm trying to transfer files from a firewire external hard drive (partitioned as os x) to a usd external hard drive (partitioned as fat 32) but the transfer rate is very slow. I can watch the file count during the transfer and it only transfers one file about every two seconds (files are 1 meg each). Since I'm tranferring over 13,000 files it takes forever. Any ideas why transferring to a usb hard drive is so slow?

USB drives are slow to start with. If you have a USB 2.0 compatible drive (and the computer has USB 2.0 supported ports) you can expect average transfer rates that are about 60 percent those of FW400. To aggravate the matter your USB drive is formatted FAT32. That slows it down even more.
You could speed things up by putting the FAT32 drive in a Firewire enclosure in order to transfer files to it. Then return it to the USB enclosure in order to transfer the files to the PC. Or replace the USB enclosure with one that supports both FW800 and USB 2.0.
At the rate you observed (1 MB every 2 seconds) it should only take around 8 hours (which is considerably shorter than "forever"). Not much consolation, I know.
If you have no better alternatives and if both computers support 100BT or Gigabit Ethernet, then you might consider networking them and doing the transfer over Ethernet. You might actually achieve faster transfer rates than using the USB drive. 100BT Ethernet should be able to move the data around 3-4 MBs/second which is about 6 times faster than what you're now observing.

SERIOUSLY slow USB hard drive on the new Airport Extreme 802.11n

I have recently bought the new airport etreme 802.11n. Great little device, look wonderful on the office desk. I had some troubles getting it up and running on my machine but finaly got there in the end.
The USB hard drive is a great little addition that I was very excited about, untill I got it running. It is amazingly slow, for example I tried to copy a folder that contained 15 files which amounted to 135.6mb and it took 20 mins and 24 seconds to upload!
Is this just the speed that it should be uploading or is there somehting wrong with my settings.
I'm running on 3 bars of signal and the settings I'm using are:
connect with password (which is the same as the base stations password)
Automatically discover disks
Show in menu bar
If anyone knows the technical data for the transfer speeds and can confirm my queries I'd really appreciate it!
Thanks in advance

I have recently bought the new airport etreme
802.11n. Great little device, look wonderful on the
office desk. I had some troubles getting it up and
running on my machine but finaly got there in the
end.
The USB hard drive is a great little addition that I
was very excited about, untill I got it running. It
is amazingly slow, for example I tried to copy a
folder that contained 15 files which amounted to
135.6mb and it took 20 mins and 24 seconds to
upload!
Is this just the speed that it should be uploading or
is there somehting wrong with my settings.
I'm running on 3 bars of signal and the settings I'm
using are:
connect with password (which is the same as the base
stations password)
Automatically discover disks
Show in menu bar
If anyone knows the technical data for the transfer
speeds and can confirm my queries I'd really
appreciate it!
Thanks in advance
Does your drive meet these requirements?:
You can connect USB-based storage devices to an AirPort Extreme (802.11n). Learn which formats and protocols are supported.
The AirPort Extreme (802.11n) supports USB storage devices that have a block size of 512 bytes, and are formatted as Mac OS Extended (HFS-plus), FAT16, or FAT32. Not all USB storage devices use a block size of 512 bytes.
The AirPort Extreme (802.11n) shares storage devices based on the format used to initialize the storage device. For example, if HFS-plus formatting was used, AFP and SMB/CIFS protocols are used to share the device on the network. If FAT16 or FAT32 was used, SMB/CIFS protocols are used.
The AirPort Extreme (802.11n) works with disks that have a single partition and are not RAID volumes (no more than one volume per physical disk).
Note: Use AirPort Disk Utility to discover and mount AirPort Extreme-based volumes over the network.
William

Mac Pro slow write speed on Samsung SSD drive

Hi,
I am wondering why I get very slow write speeds on my Samsung SSD 840 Series 250 GB system startup drive in my Mac Pro (early 2008).
I get an average write speed of approx. 35 MB/s and not much more for top speed. I tested it by transfering a large file (8GB, .m4v) from my Mac Pro internal Raid 0 (4x 2TB Stripe Set) delivering up to 550 MB/s. The read speed of the SSD is around 270 MB/s which I consider to be OK for that I have just the 3 Gb/s internal SATA interfaces in my pretty outdated Mac Pro.
I don't see any Memory or CPU overruns or consuming system tasks while doing the tests and no other user programs except Activity Monitor is running. The following screen shots from the Activity Monitor should proove my findings:
Setup:
Samsung SSD 840 Series 250 GB (SATA 6Gb/s and 3Gb/s compatible) system startup drive. Free Space left on SSD is around 100GB of 250GB.
Mac Pro (early 2008, Model 3,1), 2 x 2.8 GHz Quad-Core Intel Xeon, 8 GB RAM, NVIDIA GeForce 8800 GT 512 MB.
OS X Mavericks 10.9.1
Samsung sais there should be 540 MB/s for Seq. Read and 250 MB/s for Seq. Write for their SSD drive.
Any hints what could be done to increase especially that low write speed of around 35 MB/s (average) on the SSD in my Mac Pro?

Really great 'The hatter' !!!
Thanks a lot for your exceptional support.
Next to my 4x discs in the 4 SATA II drive bays I have installed a additional OWC drive kit that allows me to have another 2 disks sitting in the empty bay below the CD/DVD drive and those are connected to the motherboard. So there is a lot to handle for that controller you mentionned ;-)
I will follow your guidance and boot from my 'maintenance' system on direct attached external drive, install the TRIM Enabler there as well and do the DU repair run. I always have a separate system available that gives me the chance to boot my Mac from there. And in addition I regularly use ONYX to keep my OS X clean and do the maintenance.
Anyway, you're the man of the day!
PS; I am looking forward to finally receive my new Mac Pro (late 2013) ordered on the 18th of December one of these days and then I hope that I can fly ;-)

External USB hard drive won't reformat, won't appear in Finder, error: Unable to write to the last block of the device message

So I just got a new MacBook Air and since I had an external USB hard drive (TOSHIBA MQ01ABD100 1TB) lying around, I decided to use it for back-up. Since I only have just the one hard drive, I decided to partition it into two - one for Time Machine backups, and one for general files (formatted FAT so I could use it with Windows). However, the partitioning failed and I ended up with a partition named disk1s2. Plus, it won't appear on Finder anymore, but it appears in Disk Utility.
I have tried to reformat it, but I always get the message "Unable to write to the last block of the device".
Here's the info about my drive:
Name: TOSHIBA MQ01ABD100 Media
Type: Disk
Partition Map Scheme: GUID Partition Table
Disk Identifier: disk1
Media Name: TOSHIBA MQ01ABD100 Media
Media Type: Generic
Connection Bus: USB
USB Serial Number: 1220069C
Device Tree: IODeviceTree:/PCI0@0/XHC@14
Writable: Yes
Ejectable: Yes
Location: External
Total Capacity: 1 TB
Disk Number: 1
Partition Number: 0
S.M.A.R.T. Status: Not Supported
And here's for disk1s2:
Name: disk1s2
Type: Partition
Disk Identifier: disk1s2
Mount Point: Not mounted
File System: Mac OS Extended
Connection Bus: USB
Device Tree: IODeviceTree:/PCI0@0/XHC@14
Writable: Yes
Capacity: 999.86 GB
Owners Enabled: No
Can Turn Owners Off: Yes
Can Be Formatted: Yes
Bootable: Yes
Supports Journaling: Yes
Journaled: No
Disk Number: 1
Partition Number: 2
Here's what it says when I run diskutil in Terminal:
Device Identifier:        disk1
Device Node:              /dev/disk1
Part of Whole:            disk1
Device / Media Name:      TOSHIBA MQ01ABD100 Media
Volume Name:              Not applicable (no file system)
Mounted:                  Not applicable (no file system)
File System:              None
Content (IOContent):      GUID_partition_scheme
OS Can Be Installed:      No
Media Type:               Generic
Protocol:                 USB
SMART Status:             Not Supported
Total Size:               1.0 TB (1000204884480 Bytes) (exactly 1953525165 512-Byte-Units)
Volume Free Space:        Not applicable (no file system)
Device Block Size:        512 Bytes
Read-Only Media:          No
Read-Only Volume:         Not applicable (no file system)
Ejectable:                Yes
Whole:                    Yes
Internal:                 No
OS 9 Drivers:             No
Low Level Format:         Not supported
I didn't have any data in it prior to the failed partitioning attempt, so there aren't any worries of data recovery. But I'd really like to be able to use this drive again, and save some money (external hard drives are expensive where I live). Anyone with any ideas?

I'd also like to add that repairing the disk using Disk Utility does nothing but tell me to reformat the drive. So I'm stuck in a loop here.

Lost write privileges to external USB hard drive- please help!

Hi,
I've got an external Western Digital 250GB USB hard drive that has been chugging along just fine until about a month ago, when somehow I seemed to have lost write privileges to the top level directory. I"m not sure if this happened when I installed an Mac OS update, or what, as I use the drive as backup and didn't notice it for a while.
The drive appears in the sidebar with a tiny lock icon, and when I try to copy a file from my internal HD to the external (top level directory, or drag the items right onto the icon), the following things happen:
Dialog box says "The item "foo" cannot be moved because "External HD" cannot be modified", with an authenticate button, which I then click.
After I authenticate, I get the error msg "The operation cannot be completed because you do not have sufficient privileges for some of the items."
But I *CAN** copy files directly into a folder that already exists on the external drive, but I cannot create new folders in the top level directory.
I have tried the following, to no avail:
1) "get info" on the external drive, checkign the permissions. In the Ownership and Permissions section, it says "You can Read & Write", and under details:
Owner: my account (dimmed) and access level is "read & write".
Group: my account (dimmed) Access: Read only
Others: No access
Ignore ownership on this volume (unchecked).
The fact that my account was named both as owner and group seemed odd, since in Group the access was "read only". I clicked on the little lock icon next to Owner, authenticated, and was allowed to change the Group settings. I changed the Group access to "read & Write", but it's not "sticking" -- when I close teh details field and reopen it, or close the get info window and reopen, the Group access settings go back to "read only".
2) I've also, of course, tried repairing permissions on my internal startup drive, which did not help the matter. Also in Disk Utility, I verified/repaired the offendin external USB drive (no problems), Verify/Repair permissions were dimmed for this drive (I assume becuase it doesn't have MacOS X installed on it?)
3) Searched the forums, Western Digital support, etc. and I cannot seem to figure out what has gone wrong.
4) When I connect the drive to another computer (my iBook) the situation is the same. Also, when I create a new admin user account and try to access the drive from that account, I still cannot write to the drive.
Thanks, I appreciate any tips or pointers.

The drive appears in the sidebar with a tiny lock icon, and when I try to copy a file from my internal HD to the external (top level directory, or drag the items right onto the icon), the following things happen:
Open the Terminal in the /Applications/Utilities/ folder and enter the following:
chflags nouchg
followed by a space; next, drag the disk into the Terminal window and press Enter. The lock should now be gone.
The fact that my account was named both as owner and group seemed odd, since in Group the access was "read only".
Recent versions of Mac OS X create a group with the same name whenever you create an account from the Setup Assistant or System Preferences. The Group permissions don't apply in this case.
I changed the Group access to "read & Write", but it's not "sticking" -- when I close teh details field and reopen it, or close the get info window and reopen, the Group access settings go back to "read only".
Did you get an error message after doing this?
Verify/Repair permissions were dimmed for this drive (I assume becuase it doesn't have MacOS X installed on it?)
That is correct. The Repair Permissions mechanism uses data from the /Library/Receipts/ folder on a disk to function, and this data is only present on disks which have Mac OS X installed.
(12377)

Photoshop CS3 slow w/USB hard drives.

Hello all,
I'm running into a strange problem and was hoping someone could direct me on how to fix it.
I'm running an Intel Q6600 w/4GB of ram 1.5TB in a Raid 10 (4 750GB hard drives) that I had custom built from R-Tech Computers. The machine is fast and Photoshop runs great until I hook up my external USB hard drives.
I have 4 hard drives ranging from 500GB to 1TB. When I hook them up and run Photoshop, The system slows down to a crawl. I take them off, it runs great.
Photoshop is obviously looking at the drives for whatever reason. Does anyone know of any option to tell it not to look at those drives.

Free-agent: I've done the latest bios update. It has not helped unfortunately. I am headed to ESata and when its time to replace the drives, I will replace them with ESata, but for now, I have to use what I already have.
John - Not 100% sure if I've opened them from the hard drives before or not. I may have. Will try tonight to clear the history of files that it keeps in the recently opened files and see if that helps. Unless you know of any other way to tell it not to look for any files that have been opened in the past.

External USB hard drives working very slow and/or not recognized. Help!

This probably started after my Yosemite upgrade, but my external usb hard drives either aren't working well or not being recognized. It's taking forever to write files to my external Seagate Free Agent USB 2.0 through front ports and my thumb drives aren't mounting (they have shown up for a second or two, then nothing). Is there a fix? I'm on an early 2008 mac pro with Yosemite 10.10.2.
Thanks!

Do an SMC reset using this slightly-modified procedure:
Resetting the SMC for Mac Pro, Intel-based iMac, Intel-based Mac mini, or Intel-based Xserve
1.Shut down the computer.
2. Unplug the computer's power cord.
[2a. Press the power-on button to discharge the power capacitors.]
3. Wait fifteen seconds.
4. Attach the computer's power cord.
5. Wait five seconds, then press the power button to turn on the computer.
in all cases, the stated times are recommended minimums, and there are no maximums.
Intel-based Macs: Resetting the System Management Controller (SMC) - Apple Support

Extreme with USB Hard Drive and Backup 3.1 - Slow Connection

Has anyone had any experience with Apple's .Mac Backup 3.1? I have just setup my network with the new Extreme Base Station "N" with my Express being the main base station connected to my cable modem. When I go to use Backup 3.1 to backup my user folder to the wireless external USB hard drive, it takes forever! Is this normal?

RD2516:
That's exactly what I did last night to backup my wife's MacBook Pro home folder (about 45GB). I hooked up the USB drive directly to the laptop and used Backup to make a "full" backup. (This after trying it wirelessly and realizing it would've taken all night).
Then, just for fun, I forced another backup a few minutes later. It was very quick, as expected. It spent a few minutes reading the files (64000 or so) and comparing them, but then did the very small incremental backup in seconds.
So, I think now that I have the biggest part of her home folder backed up, using Backup every night should be pretty easy.
Hope that helps.
jr
Xenon2.6 Mac OS X (10.4.8)

External USB hard drive not being recognized

Hello! I'm sure this has been posted before, but excuse my naivety with this sort of thing...
I have a mac mini 10.5.6 (1.83 GHz Intel Core 2 Duo) and I run the Time Machine function to an external usb hard drive. The hard drive worked fine (plugged into the usb port on an older keyboard), but I went out and bought a new aluminum apple keyboard (because they look so cool ^_^ ) - I plugged the external usb drive into the keyboard and it wasn't recognized, so I tried plugging the external drive directly into the mac mini, but it is still not recognized. It is not showing up in Disk Utility or in System Profiler
Help? I'd hate to have to give up this fancy keyboard...
Thank you!
Dr. E

I believe I had my external drive plugged into the (old) keyboard because with the old mac that I had didn't have a free usb port for it - so when I got the mini I just plugged things back in where they were. But I have always had the Time Machine back up to this drive (connected to the keyboard) though it has been slow (another reason I thought the new keyboard was a good idea).
I tried restarting the computer without the alu keyboard plugged in, but same problem of no drive showing up.
Here is what System Profiler has to say about my drive:
USB2.0 Storage Device:
Capacity: 93.16 GB
Removable Media: Yes
Detachable Drive: Yes
BSD Name: disk1
Product ID: 0x6830
Vendor ID: 0x04b4 (Cypress Semiconductor)
Version: 0.01
Serial Number: DEF107920F07
Speed: Up to 12 Mb/sec
Manufacturer: Cypress Semiconductor
Location ID: 0x3d130000
Current Available (mA): 100
Current Required (mA): 0
Mac OS 9 Drivers: No
Partition Map Type: GPT (GUID Partition Table)
S.M.A.R.T. status: Not Supported
Volumes:
USB:
Capacity: 92.84 GB
Available: 53.14 GB
Writable: Yes
File System: Journaled HFS+
BSD Name: disk1s2
Mount Point: /Volumes/USB
I don't know the brand or model as it has 'always' been in the case that in which it currently resides and I didn't physically buy the thing :\ I do know that no software was installed with the drive as I assumed that when I put all the old info from the original mac to the mini that it was the sort of thing that would carry over.
Sorry I'm not terribly helpful - Thank you!
Dr. E

Thunderbolt drive Read/Write speeds have significantly dropped

I got a new Western Digital Thunderbolt VelociRaptor drive. When I did speed tests on it using "BlackmagicDesign" Speed Test software initially (when empty) the drive was giving me read and write speeds of 350 MB/s. Now however I have 90% of the drive occupied with data and the read/write speeds have dropped significantly to 230 MB/s. Any ideas as to why and how I could improve this?
Thanks

ishjen wrote:
Anybody know how fast the read/write speeds are with a USB hard drive and the Airport Extreme Base Station?
Welcome to Apple's discussion groups.
Apple's AirPort base stations aren't known for fast file serving, but for most purposed they're fast enough.
I can't comment specifically on your Aperture plan, but with some software it's important to avoid simultaneous access by more than one user.

USB Hard Drives Keep Disconnecting or Not Responding

Hi,
This is a long post - but one that I hope someone can offer advice on.
The Hardware
Mac Pro running OSX 10.8 (but this has happened on all versions of the OS i.e. 10.6/.7 etc)
3 x Internal SATA Hard Drives - All working perfectly.
External Drives:
2 x Western Digital My Book 1TB USB Hard Drives
1 x Seagate 750GB Hard Drive with USB2 connectivity
2 x IcyBox Dual Bay USB2 hard Drive enclosures using JMicron Chipsets - these enclosures have 2 x 1TB Western Digital Green in each (totaling 4 TB across the 2 enclosures).
D-Link 7 Port USB2 Hub
The Problem
- USB Hard Drives connected to the Mac are ejected from the system without notice and at random times AND/OR
- The external hard drive remains mounted, but when trying to write to the drive/partitions, Finder throws an error message up saying the operation cannot be completed - error code -50.
- Time Machine: TM will back up successfully several times, before eventually throwing an error up that it cannot create the folders required on the drive.
- The only way to be able to use the drives again is either remount the drive, or in some case, it is required to completely power the drive down and then reconnect.
Re-creating the problem
I have honestly not found a sure-fire way of replicating the problem. It seems completely random. It happens when I am actually sat at the computer, but it also happens when I am away from the computer.
In the past - my Time Machine hard drive has been one of the Western Digital MyBook drives. I also used the second MyBook for SuperDuper backups (extra redundancy). The 4TB drives in the IcyBox enclosures have been used to backup my ripped movie collection.
Recently however - I decided to have 2 of the 1TB drives in the IcyBox enclosures to be TM and SuperDuper backups. I have however reverted TM back to one of the Western Digital drives, purely for testing purposes. SuperDuper is backing up to one of the 1TB drives in the IcyBox.
I am trying various things to see if I can find the issue, but it is such a random event that it is taking ages to even come close to find a problem. Sometimes the drives will stay active for a few days, sometimes only a few hours, even minutes.
Theories
I have several theories as to why my USB drives continually disconnect.
1. The D-Link USB Hub.
Could connecting the drives through the hub be causing the problem? I don't really see how, unless it is a documented case that D-Link USB hubs do not play nice with OSX? To try and rule this out I have connected the current Time Machine back up drive (Western Digital MyBook) directly to the USB port on the back of the computer. The SuperDuper (IcyBox enclosure) drive is currently connected through the D-Link hub. I have removed all the other drives from the enclosures - so at present I have only 2 external drives connected (1 x 1TB Western Digital MyBook, 1 x 1TB Western Digital Green inside one of the IcyBox dual-bay enclosures - connected through D-Link Hub).
2. JMicron Chipset
I have done a bit of research on the internet and there are a few indications that perhaps JMicron SATA-to-USB controller chipsets found in a lot of external hard drive enclosures (including the dual bay IcyBox external enclosures that I have) do not play nice with OSX. If the JMicron chipsets in the 2 IcyBox enclosures is a problem - would that cause issues with other USB devices on the USB bus off the Mac? (i.e. can the JMicron chipset in the enclosures cause devices such as the WD MyBook drives which I assume use a non-JMicron chipset, to experience similar failures?)
3. Green Hard Drives
As I have said, I have 4 Western Digital Green 1TB hard drives inside the IcyBox Dual Bay Enclosures. Could the fact that these drives are 'Green' be causing a problem? They do go to sleep after x number of minutes, but they do wake up when required. But could on the occasion when I have problems, could this be caused by the 'Green' feature interrupting OSX in waking the drives? Coupled with JMicron chipset, could this be compounding the issue?
Possible Solutions
I am prepared to spend money on replacement drives and/or enclosures etc - but I would hate to spend x amount of money and have the same problem. So I am hoping to get some advice on what drives/enclosures are more than likely to work flawlessly with OSX.
Thanks for reading!

FYI - re: the SuperDuper drive that is in one of the IcyBox enclosures.
I just opened this drive up in Finder. I heard the drive wake up, but when I came to copy a file over (tried various file sizes) - I got the error -50 message.
Here is the info from Console.
31/07/2012 23:35:52.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:52.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.000 kernel[0]: disk4s2: 0xe000c2e4 (UNDEFINED).
31/07/2012 23:35:53.320 fseventsd[55]: disk logger: failed to open output file /Volumes/Data 1/.fseventsd/0000000002478a7f (No such file or directory). mount point /Volumes/Data 1/.fseventsd
31/07/2012 23:35:53.320 fseventsd[55]: disk logger: failed to open output file /Volumes/Data 1/.fseventsd/0000000002478a7f (No such file or directory). mount point /Volumes/Data 1/.fseventsd
Also, while the drive was inaccessible, I tried 'Verify Disk' in Disk Utility - here are the results
Verifying volume “SuperDuper”
Checking file systemPerforming live verification.
Checking Journaled HFS Plus volume.
Checking extents overflow file.
Checking catalog file.
Checking multi-linked files.
Checking catalog hierarchy.
Checking extended attributes file.
Invalid leaf record count
(It should be 2 instead of 1)
Checking volume bitmap.
Checking volume information.
The volume SuperDuper was found corrupt and needs to be repaired.
Error: This disk needs to be repaired. Click Repair Disk.
Please also note that the all my external hard drives have recently been reformated using GUID part. map and HFS Journaled.

Usb hard drive - slow write speed

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