The Register today reported of expected supply problems for Western Digital, due to the severe flooding in Thailand at the moment. We are already having problems getting hold of certain hard drives, and this is sure to make the situation worse.
Slashdot had an interesting article today about how to destroy hard drives. It’s a commonly asked question, but deserves a bit of time every once in a while. Of course there are the usual physical destruction options, from the humble hammer and screwdriver, to more exotic (and dangerous) techniques like a propane furnace.
For most purposes we still advise that a simple zeroing of the whole disk is a pretty safe bet. *
Failing that, then as long as you totally destroy the platters, you are good to go. That means taking the disk apart and grinding, bending and scraping the disks to bits.
* During normal use, a hard drive will get occasional bad sectors, which are then mapped out and prevented from being used. When that same sector is requested again, a new spare sector is used from another part of the disk. With the right knowledge, it is possible to access this list of remapped / bad sectors and see if there is any useful data within them. The chances of finding anything useful in these sectors is slim, but you never know.
ZDNet has an interesting article about 4K sectors (Advanced Format), however what was more interesting was the bit about large SATA drives.
Today’s large SATA drives shouldn’t be used in 4 drive RAID 5 arrays due to the high likelihood of a read error after a drive failure, which will abort the RAID rebuild.
It is a common misconception that if you run a RAID system then you can avoid keeping backups. Although fault tolerant to a point, there are plenty of issues with RAIDs that can at best cause lengthy downtime and at worst prevent any recovery at all.
The Register reports that Hitachi have beaten Seagate to market with 1TB per platter drives. These will apparently pave the way for 4TB drives, however are currently limited to single platter options up to 1TB. I hope nobody tries to make a RAID 5 with a bunch of 4TB DRIVES. That would be asking for trouble.
We at Dataquest have been aware of the problem with 1TB Seagate drives for some time. It is pleasing to see that Apple are also recognising the problem and are offering their customers a free swap out. These drives are mainly seen in iMacs, but you may also get them in the Mac Pro so make sure your back ups are up to date.
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For Mac users who cannot get their Mac to boot, this is a quick guide to find out the level of the problem with your internal hard drive. If on start up you get to the Apple logo and beyond, then this means that your Mac can read the internal hard drive. For this to happen the drive will have carried out it’s own start up process when you pressed your mac power on button. This therefore tells you that your drive is functional to a point, but has some reading problems.
If however on start up your Mac shows a folder with a question mark, then this means that your Mac cannot read the drive at all. Therefore your drive may have a more serious problem.
Some tests carried out by the “Non-Volatile Systems Laboratory” have revealed some serious flaws with SSDs ability to be securely erased. When using standard tools designed for spinning disks, the results were understandably bad. They also tried the built-in “Security Erase Unit” command and the results of this were generally not good. After being securely erased, most of the SSDs still contained some large fragments of the test files.
Some secure erasure software would be similarly inefficient for hard disks anyway, as things like remapped or bad sectors can still contain readable data which may not be erased during the process.
The simplest solution for securely erasing any data is to completely destroy the storage media. For hard drives this means making a real mess of the platters, for SSDs it means wrecking the whole PCB, data chips and controller chips.
We are still seeing these drives failing even after nearly 4 years. This just shows that there is no specific time stamp when these drives are going to fail. So anyone out there who still owns a original mac book with its original drive needs to make sure a regular back up is in place.
Users of PGP Whole Disk Encryption for Mac are advised agains the recent system update to Snow Leopard 10.6.5. Reports of users getting stuck in a reboot loop after the update have been appearing on PGP forums. The official advice is to first decrypt, then install the update, then encrypt again. More details of this can be found on Threatpost, with links for people that have already performed the update and are now locked out of their systems.