09-06-2010
Quote:
I've seen NTFS fragment terribly when only 50% full.
Me too.
After a cleanup of a full 40 Gb NTFS drive down to 60% full I've had the M$ Windows XP defrag take 30 hours despite having 2 Gb memory fitted. After that the system ran normally.
Similarly a large unix UFS /tmp mounted partition which briefly contained 400,000 files and directories (after a programming accident) ran really slowly afterwards until re-created from scratch.
With large database systems pre-allocating the segments means that you do not have disc fragmentation but that the database engine needs to handle fragmentation.
I've seen databases left to expand dynamically which caused severe slow running due to disc fragmentation even though the database engine reported no fragmentation. A database dump/load to preallocated segments on a properly tuned filesystem cured the problem.
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LEARN ABOUT DEBIAN
ntfs-3g.usermap
NTFS-3G.USERMAP(8) System Manager's Manual NTFS-3G.USERMAP(8)
NAME
ntfs-3g.usermap - NTFS Building a User Mapping File
SYNOPSIS
ntfs-3g.usermap windows-system-device [other-ntfs-device...]
Where windows-system-device is the device containing the Windows system whose users are to be mapped to current Linux system.
And other-ntfs-device is another device containing files which are to be accessed both by the Windows mentioned above and current Linux
system.
the ntfs-3g.usermap command must be started as root, and the designated devices must not be mounted.
Typing ntfs-3g.usermap with no args will display a summary of command arguments.
DESCRIPTION
ntfs-3g.usermap creates the file defining the mapping of Windows accounts to Linux logins for users who owns files which should be visible
from both Windows and Linux.
It relies on existing files which were created on Windows, trying to locate significant files and asking which Linux user or group should
own them. When a Linux owner or group is requested, the reply may be :
- the uid or gid (numeric or symbolic) of Linux owner or group of the file.
In that situation, no more file with the same Windows owner will be selected.
- or no answer, when not able to define the owner or group.
In that situation another file owned by the same Windows user or group may be selected later so that a mapping can be defined.
The mappings for standard Windows users, such as "Administrator" or "All Users" are defined implicitly. As a consequence a user mapping
should never be defined as Linux root.
When there are no more significant files, ntfs-3g.usermap create the mapping file into the file UserMapping in the current directory. This
file has to be moved to the hidden directory .NTFS-3G in the root of all the NTFS file systems to be shared between Windows and Linux. This
requires the file system to be mounted, but the created file will not be taken into account if not present at mount time, which means the
file system has to be unmounted and mounted again for the new mapping file to be taken into account.
OPTIONS
No option is defined for ntfs-3g.usermap.
EXAMPLES
Map the users defined on the Windows system present on /dev/sda1 :
ntfs-3g.usermap /dev/sda1
A detailed example, with screen displays is available on http://pagesperso-orange.fr/b.andre/usermap.html
EXIT CODES
ntfs-3g.usermap exits with a value of 0 when no error was detected, and with a value of 1 when an error was detected.
KNOWN ISSUES
Please see
http://www.tuxera.com/community/ntfs-3g-faq/
for common questions and known issues. If you would find a new one in the latest release of the software then please send an email
describing it in detail. You can contact the development team on the ntfs-3g-devel@lists.sf.net address.
AUTHORS
ntfs-3g.secaudit has been developed by Jean-Pierre Andre.
THANKS
Several people made heroic efforts, often over five or more years which resulted the ntfs-3g driver. Most importantly they are Anton Alta-
parmakov, Richard Russon, Szabolcs Szakacsits, Yura Pakhuchiy, Yuval Fledel, and the author of the groundbreaking FUSE filesystem develop-
ment framework, Miklos Szeredi.
SEE ALSO
ntfsprogs(8), attr(5), getfattr(1)
ntfs-3g.usermap 1.1.2 February 2010 NTFS-3G.USERMAP(8)