HP Storage Linear Tape File System (LTFS) Linux and Mac User Guide

Table 2 Index update options
Potential downsidesPotential benefitsIndex is flushed to tapesync_type
• Exposure to risk of power
fails during writing
When a volume is unmounted
(default LTFS v1.1.0 behavior)
unmount
• Minimal capacity overhead
• No impact on performance
• Exposure to risk of power
fails is limited to the last n
minutes
Every n minutes during writing
(default LTFS behavior from
v1.2.0, n=5)
time@n
• Some capacity overhead
since the index is written
more frequently
• Negligible impact on
performance
• Greater capacity and
performance overhead,
especially if writing small
files
• Exposure to risk of power
fails is limited to a single
file (more if several
processes are writing to
different files concurrently)
When any file opened for
writing is closed
close
User permissions
Note that on some systems, the logged-in user may not have access rights to the tape device (such
as /dev/st0). You can address this in two ways:
• Have a super-user change the permissions on the tape device file
• Execute the ltfs command with the sudo command (such as sudo ltfs /mnt/lto5).
The second approach is recommended as this preserves the integrity of the system.
File permissions
The HP LTFS application manages a common set of file permissions for all files and users; file and
directory ownership is not recorded to tape. The only permission that is tracked is write-protect
information. Files or directories that are write-protected have their permission bits set to 555;
write-enabled files and directories have their permission set to 777. By default the user and group
information is set to that of the current user; this can be overridden by use of the -o uid and -o
gid options to the LTFS application.
File types
The HP LTFS application does not support the creation of symbolic links or hard links within the
tape file system. Attempting to create a link or copy a link to tape will result in a “Function not
implemented” error. If using the cp command to copy to tape, the ‘-L’ option may be helpful
to follow symlinks.
The HP LTFS application also does not support creation of special files and will report “Function
not implemented”.
File names
To maintain compatibility when copying files between multiple platforms, it is strongly recommended
that the following characters should not be used in HP LTFS for file names, directory names, or
extended attributes: * ? < > : " | / \
Usage details 13