Author Topic: USB Rescue media - what a shocker !  (Read 14064 times)

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olddog

  • Guest
Re: USB Rescue media - what a shocker !
« Reply #15 on: December 12, 2013, 11:21:26 PM »
Under what OS were you running the Rescue disk creation utility?

It's in my signature - Windows 7, 64 bit.
Avast 2014.9.0.2008.


stevesi

  • Guest
Re: USB Rescue media - what a shocker !
« Reply #16 on: December 13, 2013, 01:41:05 AM »
Hi
I tried several times using the same 'removable' flash drive and it always failed to format the drive correctly.
However I tried a different one (8GB Verbatim removable) and it worked.
I then tried a 2GB Lexar flash drive (Removable) and that worked too.
I then used BootIt to 'flip the RMB' so that it became a Fixed disk. When the Avast utility tried to format it, I got a 'Preparing files' message and then it simply finished (no error message). Note that when a removable flash disk is used, Avast warns that the drive will be erased. This does not happen when the drive is converted to a 'fixed disk' type.
Also note that the tool lists both removable and non-removable USB drives (even though non-removable drives won't work).

The 2nd issue is to do with the 'Drive A:' error message you get when the USB drive boots to WinPE - this occurs (it seems) because the code is looking for the \rescue folder on a removable drive.
If I make a rescue-disk.iso using the Avast tool and copy it to my Easy2Boot multiboot removable USB drive + extract the whole \rescue folder to the USB drive, then it boots OK.
If you do the same thing but to a Fixed-disk type of Flash drive or a USB Hard disk, then you get the 'Drive A:' error when WinPE boots.

So the utility does work (I used Win7-64bit SP1) but you need a reliable, removable USB drive.


olddog

  • Guest
Re: USB Rescue media - what a shocker !
« Reply #17 on: December 13, 2013, 01:58:29 AM »
I then used BootIt to 'flip the RMB' so that it became a Fixed disk...

The Lexar Bootit utility gets mixed results, it is reported to work on some model Lexar flash drives and not others. From memory it doesn't work with the larger sizes.

It also doesn't as far as I am aware work with other brands (it may be specific to a particular controller chip). It certainly doesn't work with any of the Sandisk drives I've tried. Sandisk say they have no equivalent utility for any of their products.

One of the bad aspects of this removable/non removable thing is that it is not generally specified on the packaging. The two versions of the Sandisk Cruzer Switch drives I have are identical to look at including what is written on them.  I've seen some very recent packaging that advertised the product being Windows 8 certified, or words to that extent (and they are definitely not seen as removable), but some packaging gives no indication.  As the "non removable" drives works in terms of general usage, one can't return them in most stores because they can be booted from.

stevesi

  • Guest
Re: USB Rescue media - what a shocker !
« Reply #18 on: December 13, 2013, 02:18:28 AM »
OK - just to add to my last post and revise my statement that the USB tool works ...... It 95% works because is does not seem to write a valid Master Boot Record to the USB drive!
The following was done using 'removable' flash drives.

I used a 2GB USB flash drive which I had previously used for HitmanPro. When I booted from it after running the Avast USB installer tool - it still booted to HitmanPro. The drive itself contained the correct Avast files and folders. To prove it, I installed a standard MBR using RMPrepUSB and it then booted to Avast Rescue just fine.

In a 2nd experiment, I wiped the bytes in the MBR but left the partition table intact on the working Verbatim drive I used earlier. I then reinstalled Avast on it and the MBR was NOT changed and of course it did not boot.

If I wipe a USB flash drive using RMPrepUSB - Clean, then the drive is not listed by the Avast USB tool. So it needs a partitioned/formatted USB drive but it assumes that it contains boot code in the MBR of the flash drive.

I suggest that people therefore format their flash drives using  RMPrepUSB (as FAT32+HDD) or a similar tool to ensure that it contains valid boot code in the MBR (first sector).
If you format using Windows 7, it may format the drive as a floppy disk with no MBR and therefore it will not boot to Avast WinPE. You can check that it has a valid MBR and partition table using a suitable utility (e.g. RMPrepUSB - Drive Info - 0).

As many store-bought flash drives come ready-formatted and don't contain MBR boot code, this may explain why it doesn't work on some flash drives...?





« Last Edit: December 13, 2013, 02:20:36 AM by stevesi »

olddog

  • Guest
Re: USB Rescue media - what a shocker !
« Reply #19 on: December 13, 2013, 08:37:03 AM »
It 95% works because is does not seem to write a valid Master Boot Record to the USB drive!

I raised some of the problems relating to making an Avast USB rescue drive on Ticket  #LSI-274-95323 back on 12th of November. After some further correspondance where I it was elevated to Level 2 on 19th November and subsequently sent to developers on 22nd November. on 25th November I pointed out that Avast was not properly writing some of the first 512 bytes on the drive, and the results varied depending on what format was placed on the drive prior to the Avast process.

I have heard nothing since.  I assume it is still with the developers.