9.5

Table Of Contents

41 Paragon NTFS&HFS+ for Linux 9.5

10.6 Why a lot of memory is used for volume mounting?

Let us describe what’s going on when UFSD driver mounts volumes.

First of all, the driver must read ﬁle system boot record, and after verifying it, it must also read some

metadata from the mounted volume, namely, parts of $Mft and the entire $Bitmap metaﬁle. For

example, if the volume has $Bitmap of 74 MB, the driver has to read not less than 74MB to mount

it. When our driver reads data from disk, Kernel keeps the data cached in memory. The amount of

memory that Kernel allocates for I/O buffers is printed in line #3 of /proc/meminfo ﬁle (Buffers:

XXXX kB). It’s up to Kernel to decide how much memory to allocate for I/O buffers (this can be

tuned via Kernel metaﬁles – please see the link below for more information). The memory (allocated

for ‘Buffers’) is normally reclaimed by kernel when Kernel or an application needs to allocate some

memory for ‘private’ use.

The real-time report on memory allocated by our driver for operations on speciﬁc partition that is cur-

rently mounted, is available in line #2 of ﬁle /proc/fs/ufsd/<block_device_name>/volinfo.

Peak amount of memory allocated by UFSD driver when mounting NTFS volume is around 250 KB.

The amount then reduced to 40 KB after mount operation is completed.

10.7 Why the disk can’t be dismounted?

When you try to dismount the disk with the ’umount’ command the volume is reported ’busy’ and can’t

be unmounted. Why?

This issue can happen when there are working processes, that are still using the volume. There-

fore, there are several options to remove the conditions that prevent the storage medium from being

unmounted:

1. Check if it is possible to safely unmount the storage using the system’s web interface.

2. Check if support for external storage can be disabled from the system’s web interface. Disable the

services and retry unmounting the storage medium.

3. Check if the various ﬁle/media sharing services (like multimedia, SAMBA (SMB), AFP, etc) can be

disabled from the system’s web interface. Disable the services and retry unmounting the storage

medium.

Note: Windows system keeps SAMBA connection to the storage for several minutes. Disable the

connection and retry to unmount the storage medium. For example in Windows XP it can be done from

’Disconnect network drive’ menu (e.g. ’My computer’ -> ’Tools’ -> ’Disconnect

Network Drive’ menu).

If the volume couldn’t be unmount with these steps, use ’sync’ command to ﬂush buffers to the

storage medium before detaching it manually from the device:

# sync

It is recommended also to add ’sync’ command before ’umount’ to the unmounting web-interface

script, as it helps to avoid ﬁle system corruption on the storage medium, if unmount script was unsuc-

cessful and the drive was detached manually.