Working inside a broken hard drive today we came across some of the most damaged read / write heads we have ever seen. First, below is an example of how the heads should look. Notice how straight they are at the ends. Then below are the damaged heads. They are at 90 degrees to the discs (tomb stoning) and would have been scraping the inner disc surfaces to pieces. Bad times!
If you ever hear scraping, scratching or screeching noises from your hard drive, turn it off as soon as possible. If left too long, it could scrape all of the magnetic coating off the discs until there’s nothing left to recover.
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.
Cult of Mac have warned of an exploit in the Skype app which allows hackers to execute code on your device simply by sending a chat message. iPhone and iPod Touch are both affected. Skype is apparently aware of the problem and will be fixing it soon. Meanwhile be careful!
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.
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.
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.
Sophos have recently announced a free version of their Antivirus software for Mac. The software has low system requirements and will find and quarantine Mac and Windows viruses, trojans and worms.
One word of caution comes from a Mac user who lost his entire Time Machine backups while using the new software. Sophos have been quick to mention that their software has been used on Macs for many years, and by hundreds of thousands of new free users without problems.
What this really shows is that if you delete files from you mac then your Time Machine volume is no longer a backup but the only live copy of the files. Either make multiple backups or leave the files on the original volume after backing them up. Also be aware when installing new software that you should have backup copies of your data in case it all goes wrong.
Safari Mac Users need to disable Autofill within preferences. Apples browser defaults autofill to allow malicious websites access to your details from your address book without consent. This can potentially be used for identification fraud.