You have probably come across this error message from grub4dos. It occurs when the file that it is trying to use is not contiguous.
To fix this you can run
RMPrepUSB and select the USB drive and press
Ctrl+F2 to run
WinContig and defragment all
files on the drive.
Making all file contiguous on a drive is not the same as defragmenting the drive. Defragmenting a drive shifts all the files to the beginning of the drive but often does not make
all the files contiguous. WinContig does not shift the files if they are already contiguous and so WinContig is quicker and more effective than defragging the whole drive using a defrag utility.
Note: WinContig, Defraggler and other similar utilities usually need a contiguous run of free clusters on a drive so that they can copy the file into that contiguous space. Even after you run WinContig/Defraggler, you may not be able to copy over another large file and make it contiguous (even though there is enough free space on the drive) - see
this post for details. Defraggler has an option to 'Defrag Free Space' which will fix this problem.
This Defraggler map shows that the free clusters are not in one contiguous block. See here for more details.
To make a file contiguous,WinContig has to create a new file that is contiguous before it can delete the old non-contiguous file. Thus we need some
contiguous free space on the drive that is the same size or larger than the size of the file we are trying to defragment. So for a 3GB file, we will need at least 3GB of contiguous free space on the same drive.
A file in a volume exists as a number of clusters (chunks of data). For example, a typical cluster size on an NTFS volume is 4K or 8 sectors. So a 10K file would occupy 3 clusters:
Cluster 1 = first 4K
Cluster 2 = 2nd 4K
Cluster 3 = 3rd 4K cluster (only first 2K of which has valid data)
These clusters can be anywhere within the volume. So they could be at cluster no 6,7 and 8 or they could be at cluster no. 3234, 44564 and 332!
A utility such as WinContig will rearrange the clusters within a file (if it can). So in the previous example, we might end up with the file consisting of cluster no.s 3234, 3235 and 3236 and so the file is contiguous and has sequential cluster numbers.
Recently, a user on reboot.pro had a problem. He had a 6GB VHD file on an 8GB NTFS-formatted USB drive. He ran WinContig but it would not make the file contiguous. Even copying the file to a freshly formatted 8GB NTFS drive did not work, the file was always non-contiguous.
It turns out that the reason for this is that when you format an NTFS volume, the Master File Table (MFT) is placed at the 3GB position within the volume (if the volume is over about 5GB). So on a freshly formatted 8GB volume, we have
(3GB of free space)
$MFT (NTFS 'directory')
(4.7GB approx. of free space)
So we can see that there is
no way we can store a 6GB sequential file with the MFT placed at the default 3GB position.
As the file is greater than 4GB, we cannot use a FAT32 filesystem (as FAT32 does not support files greater than 4GB).
You can see this if you use a utility such as
Auslogics defrag tool which shows a map of the used clusters and what files occupy which areas of the disk.
Piriform's
Defraggler is another good tool for displaying fragmented files and analyzing the file layout on a drive. It can also defragment individual files too (right-click in Explorer) and also offers to delete files in the Recycling Bin before defragging.
Alternatively, you can boot to grub4dos from the USB drive, go to the grub4dos shell (press c in the grub4dos menu) and then use the
blocklist command to see how many fragments you have and where they are located - e.g.
So how can we make an 8GB USB flash drive containing a 6GB
contiguous file?
Well, Wonko the Sane (from reboot.pro) came up with the idea of making a small NTFS volume and then re-sizing it (expand it), thus leaving the MFT in the same place (as it is not normally moved when resizing).
Here is how to make a bootable 8GB USB drive containing a 6GB contiguous file using the partitioning tool
EaseUS Home Partition Master (EHPM):
1. Erase all ptns on the 8GB flash drive
2. Make a small 20MB NTFS PRIMARY ptn using EHPM - or RMPrepUSB if you want a special bootloader
3. Re-Size the ptn using EHPM to ALMOST the full drive capacity - e.g. 7.8GB
4. Now add a small 2nd FAT PRIMARY partition (this is to improve boot compatibility with some BIOSes - the ptn is not actually used)
5. Copy over your large 6GB file and check it is contiguous using WinContig.
If you have Vista or Win7/8, then you can use Disk Manager instead of EaseUS Home Partition Master.
The whole discussion can be found on reboot.pro
here.
Having trouble still? See also my other blog article
here.
