"Unable to write to the last block of the device"

Thanks. Worked like a dream. I did it from Ubuntu on my VMware Fusion partition.

I had the same problem with my old internal disk which used to hold my home folder.

After replacing it with a new one I hooked it up to a SATA to USB 3.0 and wanted to format

the drive. I first got an error that the drive could not be unmounted.

After force unmounting the drive with terminal I got the famous "could not write to last block" error.

I tried formatting on my macbook pro, 2 imac's and a windows 7 laptop,

all with no succes.

What did the trick for me was breaking open my external harddrive and hook up the drive in there.

Connect it with the firewire 800 cable to my macbook pro and formatted the drive with no prob.

apparently for my drive it was a USB conflict...

I was able to salvage two drives today using FireWire 800.

Both drives failed during a change from Apple partiton to GUID using USB. No matter how I tried I couldn't get past the Failed To Write Last Block message. (or something like that)

I pulled the drive(s) from the external USB drive and plugged into a FireWire drive and Presto no problem creating a Bootable Intel Partition. GUID (Using Disk Utility in Lion) The drives now work in the USB enclosures.

Some drives may fail due to mechanical failure but many are disabled due to some kind of bug. I am quite sure about this.

Good luck, I hope some good Hard Drives can be salvaged using this method.

This was the most effective solution when I encountered the "unable to write to the last block" error. Thanks.

I just encountered this exact same error with my external WD HDD, after trying to erase it with Disk Utility.

Spent the last 4 hours trying everything to make it work, Terminal, Recovery Boot, Disk Utility, Different Mac etc.

At last I fell upon another thread about the POSIX input/output error. In this thread it was suggested to try GPARTED Live or iPartition.

So that's exactly what I did. I got a hold of the latest version of iPartition (I know it's a quite expensive app, but it's got a demo version, and can be acquired from other sources as well 😝)

Anyway, iPartition finally enabled me to fully erase my external drive, add a new partition and now I can use the HDD for TimeMachine again.

I had a faulty flash drive which iPartition succesfully reformated and it's now fully working.

Friggin brilliant tool. I can only recommend anyone with the POSIX: INPUT/OUTPUT error, or the above stated "Unable to write to last block of the device" error to try it out. Helped me a lot, and saved me a lot of time and money.

I saw somebody else post this and I tried it and it worked. Run Disk Utility from the Recovery Partition. Easy.

For step-by-step:

- Reboot into Recovery Partition (hold option when restarting).

- run Disk Utility

- Format drive like you normally would

- Boot back into regular partition

I don't know why Disk Utility didn't work from normal startup.

I don't know if this will solve your problem, but it worked for me. And I think I tried every other suggestion before doing this. My setup:

- Internal drive is a 4TB Seagate ST4000DX000 pulled out of a Seagate Backup+ USB3 case

- Connection is via one of the "extra" SATA ports on 2008 Mac Pro

- Mac OS X 10.8.4

Hey, Cbjornsen - I got mine to work the same way, almost. I went to zero out an old 40gb IDE laptop drive that I hadn't been using for a while and partway through, it gave me an error. From that point on, I just kept getting the "unable to write to the last block of the device" error. I could erase the Volume in Terminal and get it to mount as an unformatted drive, but every time I tried to format it, whether in Terminal or from the Recovery Partition or from my regular Mountain Lion install, it gave the "unable to write to the last block of the device" error again and I had to re-erase the Volume in Terminal. Finally, I went with iPartition. Kept getting an error trying to create an Apple or GUID partition map, but it worked when I chose the Master Boot Record. Then I formatted as a FAT32 volume, and now it works fine. I was going to try reformatting now that it's working as Mac OS Extended, but thought better of it and just quit while I was ahead.

Three different USB devices on 2 different 10.9 Macs. In the process of extended "writes" of data (1 or more hours) the devices work for a while then I get the message that the computer lost the connection with the device. Now, when I attempt to mount the device, I get the message: "Unable to write to the last block of the device" Tried several tricks including a demo version of iPartition. I may continue to try to mount the device but I am concerned that this error will keep occuring. Appears to happen when there is a long write process to the device. Same message with 2 USB flash drives (one brand new) and one 2T Segate external USB drive. Very odd! One computer is a brand new Powerbook Pro with USB3 and the other is an older 27" iMac with USB2.

After being on the phone with level 2 technical support, we turned off hard disk sleep, power nap and computer sleep on both devices and a 4 hour write went with out problems. Now if I could just get my 2TB drive back! Will try the genious bar after I return from a trip. Tech support said the soon to be released OS update will fix this.

Awesome! This definitely helped ! Nothing else needs to be done. Quick and Easy! Thanks !

Hello friends

I also got the similar errors as "Unable to write to the last block....". Initially, I did not believe it could be due to faulty HD cable. After going through the forum, I decided to give it a trial of replacing the HD cable. It worked like a new MacBook pro after replacing the cable. Very intresting that faulty HD cable can give an error which seems to be either Hard Disk related or Software bug,

Thanks to everyone for their great efforts of sharing the experience.

Cheers

Ajay

In my case it was with a LaCie Pocket Drive 10GB.

This is a FireWire400/USB drive.

I always used it on FireWire as then it draws the power it needs from FireWire.

When I tried to Erase from Disk Utility (OS X 10.7.5) on the disk using the FireWire400 interface I got this error.

After trying again a few times (and cursing), I Googled this and noticed some disks have firmware issues.

Thinking that maybe the firmware handles FireWire and USB differently, I though I might as well try the USB interface.

Found the original box with the power brick (needed when on USB) and also a USB cable in the box.

Tried it and it worked!

So I did not have to resort to trying to find revised firmware, and loading it onto the drive,

which may have required trying to interact with the drive via Windows under Parallels.

Not sure that would have worked!

Anyway, allowing for my time it probably would have been cheaper to buy a 16GB memory stick.

This issue still remains in Mavericks (10.9.5) Booting with Cmd-R worked for me. It seems Apple is not too worried about us Mac users... being this a known issue...

Re

umairycApr 7, 2012 4:00 PM Re: "Unable to write to the last block of the device"
Re: "Unable to write to the last block of the device"in response to nickspassov

I cant figure out how to do the same in lion, however, this is how you fix a corrupt usb in windows 7:

Thanks for these simple clear instructions

A lifelong Microsoft user and in retirement using Apple I am surprised that, while most things apple are easy this was difficult and solved by using microsoft cmd.

The last step returned 0% format but when I went to windows file manager and tried to format the 16Gb USB it worked

Thanks for saving an expensive piece of kit!!

PS It was my fault for accidentally removing the USB drive while something was writing to or reading from it and corrupting the contents hence the "unable to write to the last block of the device" error

For information I am having the same problem with a new Samsung SSD 850 EVO internal solid state drive in a Macbook Pro 7,6. I was booting in Option/Command/R.

Have tried two examples, same problem. I guess I could contact Samsung, but would rather just get another drive.

Could it be a problem with the older (mid 2010) machine?