Klennet Recovery Settings

When adjusting settings, keep in mind that:

• changes to recovery parameters do not apply to recoveries already in progress;
• changes to display and visual parameters do not apply to currently open pages.

General

Reset hidden tips

Click this to show all the hints and tips again, clearing all Do not show again checkboxes.

Show tips on toolbar buttons

The pop-up tips on toolbar buttons are helpful when working with Klennet Recovery for the first time, especially to figure out why the button you want to click is disabled. However, professional data recovery technicians may find them annoying after a while. When you know which button does what, uncheck this setting to disable all the pop-up tips.

Remove duplicate empty files

If you enable this option, Klennet Recovery cleans up empty files (files with no data in them, having a size of zero).

• If a directory contains multiple empty files with the same name, the filter removes all but one.
• If a directory contains a subdirectory and one or more empty files with the same name as the subdirectory, the filter removes all the empty files, leaving only the directory.

Filesystems to scan

You can choose the filesystems Klennet Recovery should look for. The default setting is to enable all filesystems, which generally works fine.

There is one case when selecting individual filesystems is useful. If you are recovering a volume full of virtual machines and all filesystem types are enabled, Klennet Recovery will recover both the "outer" volume (containing the VMs) and all the "inner" volumes from inside the VMs. This will use some extra memory and generally produce a mess. If the volume you are recovering contains virtual machines, consider selectively disabling the filesystems you do not need.

Temporary files

Klennet Recovery does not require any temporary disk space when run with the default settings. However, BTRFS recoveries involving checksums require a significant amount of swap space (see below for estimates).

This temporary space must be on an SSD. The rotational hard drive does not provide enough performance to be useful. The default is to use the system default temporary location. However, you need to make sure it has enough space and is pointing to an SSD.

FAT16/32 filesystem settings

Short file name encoding

FAT filesystem uses Unicode for long file names but DOS OEM encoding for short file names. You only need to adjust this setting if the locale of the PC on which you perform the recovery does not match the locale of the original filesystem and short file names in the national language come out garbled. In practice, this situation is rare because, in most cases, the driver writes Unicode long file names anyway.

NTFS filesystem settings

Filesystem parameter detection

This option controls how Klennet Recovery determines the filesystem parameters, notably the cluster size. NTFS keeps these parameters in the boot sector. If the boot sector is damaged, the recovery algorithm determines the correct parameters based on the data on the volume.

However, the task becomes complicated when the volume stores virtual machine disk images (like VHDX images), also formatted as NTFS. In this case, the volume holds several incompatible sets of metadata, one for the volume itself (the "outer" set) and one for each disk image stored on the volume (the "inner" one). The algorithm often gets confused because it cannot differentiate between the "inner" and the "outer" parameter sets.

On the other hand, even if the volume is formatted, the format procedure selects the same parameters because the parameter set is chosen based on the volume size.

In summary, the recommendation is to select Use boot sector if available unless you know the volume was re-formatted with non-default cluster size.

BTRFS filesystem settings

Use checksums for file validation

BTRFS uses checksums to verify that the file content is correct. Klennet Recovery can use the same checksums during file validation. However, this requires temporary SSD space (see the Temporary files setting above).

Klennet Recovery uses about 2% of the total disk size to hold temporary information to enable checksum validation.

Reconstruct missing chunks

BTRFS may require a special recovery mode, which is rather slow requires even more temporary SSD space. Please see BTRFS-specific manual for more details.

Reference temporary disk space usage

Disk size to scan	1 TB	5 TB	10 TB	20 TB	50 TB	100 TB
Checksum validation	20 GB	100 GB	200 GB	400 GB	1 TB	2 TB
Chunk reconstruction	50 GB	250 GB	500 GB	1 TB	2.5 TB	5 TB

Temporary disk space requirements for BTRFS recovery features

LVM2 partitioning settings

LVM2 (often called just LVM, short for Logical Volume Manager) refers to a RAID and partitioning scheme used in Linux and various NASes.

Klennet Recovery reads LVM2 metadata as a part of the Read RAID metadata function. The settings below apply only to thinly-provisioned LVM volumes.

Flatten multiple nested partitions

LVM2 internally organizes its volumes by combining multiple levels of nested components. If enabled, this option will reduce the complexity of the layout by flattening it whenever possible, replacing multiple nested levels with a single equivalent component.

In effect, it will change a partition at adddress 1024 on a partition at address 1024 on a partition at address 1024 on disk X into a partition at address 3072 on disk X.

Extended search for thin volumes

In contrast to a regular partition, a thinly-provisioned volume may store its data blocks in any order. LVM tracks the location of each volume block using the block map in the designated metadata area on the disk. LVM deletes the reference to the block map when the volume is deleted, but the map itself remains in the metadata area until it is overwritten by subsequent use. If Extended search for thin volumes is enabled, Klennet Recovery scans the entire metadata area for remnants of the volume maps. It presents each of the found maps as a separate volume.

• The search takes a long time because the metadata area may be as large as 64 GB.
• The search will likely produce hundreds of volumes, each representing a different (and probably damaged) version of the same volume.

Add contiguous missing blocks

If part of the block map is missing (probably because it was overwritten) and it looks like the missing part of the volume was allocated contiguously, Klennet Recovery will add the missing blocks. The side effect is that sometimes the added blocks belong to another volume. However, the added confusion is usually minor, so I recommend enabling this setting.

This setting is only effective when "Extended search for thin volumes" is enabled.

Drive failure handling

This section specifies an external program to launch when a drive failure is detected. You should use it along with a software-controlled power or USB relay. For details, please refer to the dedicated page.