I notice the Linux based software at Synology for my NAS backs up 'free space' (unused space on the hard drive) as well as space that has data. I am used to Macrium Reflect only backing up data.

Why is that? I've seen this before mentioned in the literature. Below is a mention from a quick Google search.

RL

In attempt to use Clonezilla or DD terminal tools in Ubuntu, it seems that making an image of the 1TB drive is going to make a full 1TB backup image file on our network storage which is a large waste of time and space being as there is only about 25gb of "used space" on the drive.

Any suggestions for making a quick all-partition image-file backup of a windows hard drive that will result in an image file of the same size as the "used space" ?

On 6/21/2022 1:26 PM, RayLopez99 wrote:
> I notice the Linux based software at Synology for my NAS backs up 'free space' (unused space on the hard drive) as well as space that has data. I am used to Macrium Reflect only backing up data.
>
> Why is that? I've seen this before mentioned in the literature. Below is a mention from a quick Google search.
>
> RL
>
> In attempt to use Clonezilla or DD terminal tools in Ubuntu, it seems that making an image of the 1TB drive is going to make a full 1TB backup image file on our network storage which is a large waste of time and space being as there is only about 25gb of "used space" on the drive.
>
> Any suggestions for making a quick all-partition image-file backup of a windows hard drive that will result in an image file of the same size as the "used space" ?
>

I don't know BTRFS or ZFS at all. I also don't use them on
any installation here, because I don't know how they work.
BTRFS has fast write and fast snapshot capabilities, but usually
any time a certain parameter is "optimized" on something,
there is a hidden cost somewhere else.

EXT goes up to version 4. EXT4 has a journal, that provides
some ability to correct the state of the file system, when it
starts up. This, presumably, has a storage cost. The journal on
NTFS, some utilities report the address of a pointer, as if it
is the size of the journal. When other utilities seem to indicate
the journal only keeps the last 32 megabytes of entries.

When Macrium backs up EXT4, it does recognize which inodes are
occupied and which are not occupied. If a partition has 20GB of data,
it might take 30GB to store it.

Whereas when an NTFS partition reports 20GB of data, that includes
all metadata ($MFT), and so the backup is also 20GB in size.

Both EXT4 and NTFS use "smart backup", so only the occupied parts
are stored. If a partition is 1TB and it contains 20GB of data,
the .mrimg is 20GB for NTFS and 30GB for EXT4. The other 970GB or
so, is not captured.

It is when Macrium is asked to back up a partition it does not
recognize (Linux SWAP), it backs up the whole thing, dd-style.

Make sure what you're backing up, is a recognized type. If it is
not a recognized type, you're using the wrong backup tool.

Clonezilla is a package of scripts. It uses ntfsclone (a program
from ntfsprogs), to clone a partition. I believe that's a smart
tool as well, but I've only tested that once and don't use that
regularly. I have no operating statistics to share on that.

*******

Unix and Linux OSes, support "reserved space for root". You may
be able to fill a partition to 95% as a user, and be told it is
full. As root, it will show 5% space remaining. This allows root
to do space management maintenance on the machine, without some
processes croaking as they are out-of-space.

*******

One way to make a dd backup, is to:

1) Zero out the white space on the drive. On Windows, this is

sdelete -z C:

On Linux, it would be (roughly)

dd if=/dev/zero of=~/big.bin bs=1048576

which runs until the volume is full, then immediately
you do this to relieve the pressure

rm ~/big.bin

Now the white space is all-zeros.

2) sudo dd if=/dev/sda bs=8192 | gzip -c > mybackup.dd.gz

This compresses all the all-zero parts of the volume,
reducing the space needed. 20GB of data on a 1TB drive,
now needs less than 20GB for mybackup.dd.gz .

You reverse the procedure for restoration

gzip -c -d mybackup.dd.gz | sudo dd of=/dev/sda bs=8192

Now, all of that is from memory, so those commands need
to be tuned and corrected. That's just to show the basic idea
of making a small dd backup. Zeroing out the white space is
critical to doing a compact "dumb" backup, versus the Macrium
"smart" backup.

If you're having trouble with your /dev/sda, select an OS
which has this command:

sudo disktype /dev/sda

and show me the output.

*******
This is my Windows drive. You will notice it is not
able to name the partitions. There are two C: drives and a Data Partition here.

PS S:\disktype> .\disktype.exe /dev/sda # A Cygwin runtime EXE, a Powershell window

--- /dev/sda
Block device, size 931.5 GiB (1000204886016 bytes)
DOS/MBR partition map
Partition 1: 931.5 GiB (1000204885504 bytes, 1953525167 sectors from 1)
Type 0xEE (EFI GPT protective)
GPT partition map, 128 entries
Disk size 931.5 GiB (1000204886016 bytes, 1953525168 sectors)
Disk GUID FD14CEF1-BB8C-5D4F-B759-93CE9F452F13
Partition 1: 100 MiB (104857600 bytes, 204800 sectors from 2048)
Type EFI System (FAT) (GUID 28732AC1-1FF8-D211-BA4B-00A0C93EC93B)
Partition Name "EFI system partition"
Partition GUID D249609A-DEE3-BE47-AD71-580FF00AB3BF
FAT32 file system (hints score 4 of 5)
Volume size 96 MiB (100663296 bytes, 98304 clusters of 1 KiB)
Partition 2: 16 MiB (16777216 bytes, 32768 sectors from 206848) <=== no file system...
Type MS Reserved (GUID 16E3C9E3-5C0B-B84D-817D-F92DF00215AE)
Partition Name "Microsoft reserved partition"
Partition GUID 24B5AF81-CD1B-CA49-8F48-F64A4DF5DD2B
Partition 3: 118.8 GiB (127538298880 bytes, 249098240 sectors from 239616)
Type Basic Data (GUID A2A0D0EB-E5B9-3344-87C0-68B6B72699C7)
Partition Name "Basic data partition"
Partition GUID 2DACEFA6-A55C-E74E-AB9A-3D6D5DA32DCA
NTFS file system
Volume size 118.8 GiB (127538298368 bytes, 249098239 sectors)
Partition 4: 593 MiB (621805568 bytes, 1214464 sectors from 249339904)
Type Unknown (GUID A4BB94DE-D106-404D-A16A-BFD50179D6AC)
Partition Name ""
Partition GUID D35EEEA1-434A-4E47-8AE1-CF26BF5F3120
NTFS file system
Volume size 593.0 MiB (621805056 bytes, 1214463 sectors)
Partition 5: 130 GiB (139586437120 bytes, 272629760 sectors from 250556416)
Type Basic Data (GUID A2A0D0EB-E5B9-3344-87C0-68B6B72699C7)
Partition Name "Basic data partition"
Partition GUID 7005B26D-00BE-F242-A32E-808D3682CC32
NTFS file system
Volume size 130.0 GiB (139586436608 bytes, 272629759 sectors)
Partition 6: 413.8 GiB (444283748352 bytes, 867741696 sectors from 523186176)
Type Basic Data (GUID A2A0D0EB-E5B9-3344-87C0-68B6B72699C7)
Partition Name "Basic data partition"
Partition GUID 552F9D87-B14C-FC48-A535-65CC406EFA44
NTFS file system
Volume size 413.8 GiB (444283747840 bytes, 867741695 sectors)
Partition 7: unused

PS S:\disktype>

*******

This is a legacy partitioned disk, with Linuxes on it. As
listed by one of the Linux OSes. It uses Extended/Logical
for some of the partitions. They're not all Primaries.

Even the gnome-disks diagram, isn't entirely correct.

[Picture]

https://i.postimg.cc/NMj3H4dd/linux-disktype.gif

bullwinkle@FOSS2004:~$ sudo disktype /dev/sda # A Linux executable, in bash

--- /dev/sda
Block device, size 931.5 GiB (1000204886016 bytes)
GRUB boot loader, unknown compat version 1
DOS/MBR partition map
Partition 1: 976 MiB (1023410176 bytes, 1998848 sectors from 2048)
Type 0x82 (Linux swap / Solaris)
Linux swap, version 2, subversion 1, 4 KiB pages, little-endian
Swap size 976.0 MiB (1023401984 bytes, 249854 pages of 4 KiB)
Partition 2: 104.5 GiB (112253206528 bytes, 219244544 sectors from 2000896, bootable)
Type 0x83 (Linux)
Ext4 file system
Volume name "UBUNTU"
UUID DCF6AA27-5B1A-4B93-9051-64F14EC3C262 (DCE, v4)
Last mounted at "/media/bullwinkle/UBUNTU"
Volume size 104.5 GiB (112253206528 bytes, 27405568 blocks of 4 KiB)
Partition 3: 64.00 GiB (68719000064 bytes, 134216797 sectors from 221245440)
Type 0x83 (Linux)
Ext4 file system
Volume name "LINUXMINT"
UUID C1694081-841D-4B48-BC6F-9A6CF88C8DAE (DCE, v4)
Last mounted at "/"
Volume size 64.00 GiB (68718997504 bytes, 16777099 blocks of 4 KiB)
Partition 4: 546.6 GiB (586891270144 bytes, 1146272012 sectors from 355465214)
Type 0x05 (Extended)
Partition 5: 70.31 GiB (75497000448 bytes, 147455079 sectors from 355465214+2)
Type 0x83 (Linux)
Ext4 file system
Volume name "GENTOO"
UUID D2BA30EB-D077-42FF-823B-828BB49B78FF (DCE, v4)
Last mounted at "/mnt/boot-sav/sda5"
Volume size 70.31 GiB (75496996864 bytes, 18431884 blocks of 4 KiB)
Partition 6: 413.8 GiB (444282699776 bytes, 867739648 sectors from 502920295+2969)
Type 0x07 (HPFS/NTFS)
NTFS file system
Volume size 413.8 GiB (444282699264 bytes, 867739647 sectors)
Partition 7: 62.50 GiB (67109000192 bytes, 131072266 sectors from 1370662912+2048)
Type 0x83 (Linux)
Ext4 file system
Volume name "U2004"
UUID 157E24F1-04D9-4D9D-BE54-D68A8004FBA4 (DCE, v4)
Last mounted at "/"
Volume size 62.50 GiB (67108864000 bytes, 16384000 blocks of 4 KiB)

That utility, at least, should tell you the file systems involved.

Paul