Month: August 2020

Over the years, Iomega external disks have been very popular drives in Ireland for their ease of use and wide variety of capacities. Using a 3.5” or 2.5” form factor, these disks usually come in a brushed aluminum or plastic lacquered enclosure. The 3.5” version such as (MDHDU500) comes with a 12V 2A power adaptor while the 2.5” variants (such as LPHD-UP and RPHD-TG) are USB bus powered. Given their popularity, it’s no surprise that we see a lot of them in our lab for data recovery.

Inaccessible Iomega external disks can show many symptoms including:

• Your Iomega disk appears as “unformatted” in Windows.
• Your Iomega external hard disk is not getting detected by your Windows, Mac or Linux computer.
• When your Iomega disk is connected to a Mac, you receive the message “the disk you inserted was not readable by this computer”.
• Your Iomega external disk will not turn on.
• Your Iomega external disk shows a flashing light, but no data appears.
• Your Iomega disk is making a clicking, buzzing or knocking sound.
• You are presented with an error message about “the parameter is incorrect” or “cyclical redundancy check” when you connect your Iomega disk’s USB cable.
• You can see your files and folders on your Iomega disk but cannot copy them over to another medium.

Or, a specific event may have occurred to your disk which has resulted in it failing such as:

• Your Iomega external disk has suffered a suspected power surge
• Your Iomega external disk got accidentally dropped.
• You accidentally formatted your Iomaga hard disk containing priceless photos.

Recently, we had a customer whose Iomega external disk contained all their work for the last seven years but stopped working unexpectedly. Their 3.5” MDHDU500 Iomega disk failed to be recognised by any of their Windows computers. We opened the enclosure and found a Seagate Barracuda 7200.11 500GB S-ATA disk (ST3500820AS). Our recovery systems indicated that the disk appeared to be in continual “Busy” mode. This means that the disk could no longer receive ATA commands needed for  diagnostics or repair. When a disk is in this mode, it’s like trying to call a telephone number, but continually getting the engaged tone. Either the person’s phone is busy or there is a problem with their connection and/or phone.  In this case, any ATA commands we issued to the disk to initiate an exit from this very restrictive mode of operation proved fruitless. We did not suspect the disk-heads because platter and head-disk assembly rotation sounded normal. Moreover, we had come across similar problems with this family of disks before.  The problem is usually – but not always – rooted in a faulty media-cache. The media-cache in these disks buffers sequential and random writes so they write more smoothly to the disk. (It should not be confused with the media-cache used in SMR disks) However, the media-cache can sometimes go corrupt causing the disk to be unreadable.

Fixing the Iomega External Drive and Recovering its Data.

In order to get the disk to exit “Busy” mode, we had to short the read-channel of the disk. This can be performed by using an anti-ESD tweezers and applying its two tongs to two shorting points on the disk’s PCB. Once this had been completed, we patched the ROM. Patching the ROM is like adding an extension of code onto the existing module allowing our data recovery equipment recognise the drive. This procedure got us a mountable volume again. The media-cache can an be an awkward beast to handle, but having the experience of successfully resolving this problem numerous times made this procedure less daunting. We achieved a 100% data recovery rate – over 450GB of data. We were very surprised to see that the customer was still using FAT32 as their main data storage partition though. (FAT32 should not be used on USB memory sticks let alone disks containing almost half a terabyte of important data…) We extracted his recovered data onto a USB external drive. Another happy customer. Another case closed.

Drive Rescue is based in Dublin, Ireland. We offer an external hard disk data recovery service for Iomega external USB drives which are unrecognisable, which are clicking, which are appearing as “unformatted” or Iomega drives which have been dropped. Common models we recover from include the MDHDU, MDHD500-ue, MDHD320-U, GDHDU2, LDHD-UP, LPHD-UP and Iomega Go 2.5” portable disks such as the RPHD-TG, RPHD-U, RPHD-UG and RPHD-UG3.

Data Recovery from inaccessible Samsung Evo 750 SSD

This Samsung Evo 750 SSD (MZ-750500) taken from a 2013 Apple iMac was no longer accessible to the user. Instead, this retro-fitted disk, presented him with the dreaded “flashing folder and question mark” screen. When in Apple’s Recovery Mode, the disk also failed to appear in Disk Utility. The user, an author, stored copious amounts of PDF, Word and image files on it – all of which needed to be retrieved to meet upcoming publication deadlines.

The Samsung Evo 750 is an SSD, which was introduced by the company in 2016. It uses 16nm planar-based TLC NAND, has a 512 DRAM cache and is managed by an MGX (Samsung in-house) controller.

Our SSD data recovery equipment provided us partial access to the Evo’s firmware. The wear- level of the SSD’s blocks was high and it also became apparent that the disk was over 94% full. An almost full-capacity solid-state with high-wear levels is far from optimal. This is because when some blocks go bad, the SSD controller will allocate (good) spare blocks to replace them with. This is known as bad block management (BBM). But, here is the catch, when the controller has a sparse level of blocks to choose from and those that are available are worn out – the controller can easily lock-up. We suspect this is why the user could no longer access his data.

How could this have been prevented?

First and foremost, this problem could have been prevented if the user didn’t fill his disk up to near-full capacity. It’s generally a bad idea to use an SSD that is over 90% full, without freeing up some capacity first. SSDs need some breathing space to perform essential housekeeping operations like garbage collection and BBM.       

Secondly, the user might have been prevented the problem if they over-provisioned the disk. Over-provisioning can be achieved by creating a partition that does not use the disk’s full capacity. This “unclaimed” space will then be used by the SSD controller as a pool of “spare” blocks.

In some cases, SSD manufacturers already do this in a process known as “factory over provisioning”. But, for this disk, Samsung did not factory-over-provision it. The deployment of factory over-provisioning is usually indicated by the disk having an “uneven” capacity.  For example, a 480GB disk is normally a 500GB disk, but with 20GB reserved for over-provisioning. Likewise, you can have a 960GB SSD, which is really a 1TB disk with 40GB allocated for over-provisioning.

The paucity of free blocks was not the only factor which culminated in this disk becoming inaccessible. Consistent with many earlier generations of SSD disks, this Samsung 750 Evo SSD was only using 2D planar NAND. This suffers higher rates of cell-to-cell interference than 3D NAND commonly used in SSD’s today.

Recovering the Samsung Evo 750 with a Firmware Emulator

Even though the controller on the disk appeared to be locked. We were able to use a firmware emulator to access the partition table. The emulator mimics the disk’s MGX controller, enabling us to get access to its APFS partition. Much to his satisfaction, the author got all his files retrieved and was saved the painful process of re-doing work which he had already completed. Moreover, he would meet all of his publication deadlines.

Drive Rescue is based in Dublin, Ireland. We offer a SSD data recovery service for inaccessible SSDs such as the Samsung Evo 750 (MZ-750500, MZ750250), Samsung Evo 840, Samsung Evo 850 (MZ-75E1T0) and Samsung Evo 860 (MZ-76E500BW and MZ-76E1T0b). Contact us on 1890 571 571.

Last week, a customer from Dublin contacted us needing data retrieval from their old Sony Vaio laptop. The customer, an architect, recently removed the system from a storage cupboard in his office. Its hard disk contained drawings of a project which he had completed in 2008. Recently, he got the green light for a very similar project. If he could salvage these old drawings (stored in DWG format) along with planning permission files (Word and PDF) from the laptop, he could save himself a lot of time and expedite the planning permission and design process for his customer. Could we recover this customer’s Vaio’s hard disk?

• 

The Vaio laptop running Windows 7 laptop was no longer starting up. The system was completely dead. We opened up the laptop and removed its Seagate Momentus 640GB disk (ST9640423AS). When attached to one of our Windows systems via S-ATA cable, it failed to mount. So, we connected it to one of our data recovery systems to peform a more detailled diagnosis. However, our tests to analyse the platter surface and disk-heads could not even run because the disk was not spinning. Though we did get a succesful identification of the disk’s firmware family and version number. In our clean-room, we opened the disk. The heads were not parked on the disk ramp, but rather precariously positioned in the middle of the platters.

This is not ideal because an adhesive bond can form between the disk-heads and the platter surface. This is known as “stiction” and used to be a big issue for electro-mechanical disks until “ramps” or “parking areas” were incorporated into disk designs. This design change resulted in the stiction problem being more or less eliminated for disks being stored in ambient temperatures. However, in this case, the disk evidently experienced a sudden shut down and the head-disk assembly (the component on which the disk-heads are mounted) never got an opportunity to “park”.

Using specialised tools, we “unstuck” the heads from the platter surface. This procedure needs to be performed extremely delicately. An exertion of force can lead to platter or disk-head damage whilst too little force can result in the disk-heads remaining stuck. Drive Rescue use a number of finely tuned processes and tools to perform this task in the safest possible way.  

Perfluoropolyether – the hard disk super-lubricant

In this case, while the HDA was not in a “parked” position, there is another feature of hard disk design which helps mitigate against stiction events. Manufacturers apply a very thin layer of perfluoropolyether (PFPE) to the platter surface. This “super-lubricant” is a colourless synthetic oil commonly applied to HDD platters because of its durability, chemical inertness and good cohesiveness with the platter’s carbon layer. If a minor scratch does occur, the composition of PFPE exhibits just the right amount of viscosity to replenish the disk areas that have been depleted of lubricant. Its cohesiveness means that the lubricant remains in-situ, even with the constant stress of air-flow that is generated by the slider as it moves over the platters. The qualities of PFPE also mean that it can also prevent the disk-heads forming a strong metallurgical bond with the platters.  

While PFPE might sound like a lubricant that Captain Kirk might use for greasing up the old Starship Enterprise, it is not faultless. At high temperatures, the efficacy of this super lubricant reduces, increasing the risk of tribological events, i.e. the read or write elements that come into direct contact with carbon or magnetic layer on the disk. In this case, however, PFPE seems to have done its job well. (The ambient temperature of the office where the customer stored the host laptop no doubt helped). While the disk-heads and platter had collided, they were joined by only a weak bond. If the bond had been stronger – disk-head or platter damage would have been inevitable. Thus, the need for a full head-disk assembly replacement was negated. The delighted customer was reunited with all his historic work, which was presented to him on an external USB drive. He now had some extra free time in the summer and would not have to backtrack on work he had previously completed.

Drive Rescue, Dublin, Ireland have been recovering data since 2007. We offer a complete recovery service for non-booting, unreadable or damaged disks from Sony Vaio (E, PCG. VGN-Z and VPC-Z) series of laptops. This includes disks such as the Seagate Momentus ST500LT012, ST9640423AS, HGST Z5K-500, HGST Z5K1000 and the Toshiba MQ01ABD050