Where did my HDD's capacity go?

[Nemesio Garcia]

Hi,

I've recently installed Alt-F by overriding the original DNS-323 firmware, and followed the wizard to turn my 2 x 1TB HDDs into RAID1. After completing the process, I noticed that the RAID1 capacity is 916.4GB (I expected a number closer to 1000GB), and only 869.6GB are available, which is strange because I have not copied any of my files to the drive yet. I've browsed all the directories to see if I'm able to find what's taking up this space, and I'm not able to find anything.

Is this normal? Or did I miss I miss a step? I'm willing to troubleshoot to get his resolved.

Thank you in advance!

-NG

[Joao Cardoso]

On Saturday, November 3, 2012 4:36:59 PM UTC, Nemesio Garcia wrote:

Hi,

I've recently installed Alt-F by overriding the original DNS-323 firmware, and followed the wizard to turn my 2 x 1TB HDDs into RAID1.

Disk manufacturer use 1MB=10^6=1000000, 1GB=10^9=1000000000, referring to the raw disk capacity; in informatics, one speaks of 1MiB=2^20=1048576, 1GiB=2^24=1073741824.

In Alt-F, where disk is involved, powers of 10 are used (disk capacity), and where operating system data is involved powers of 2 are used. I am afraid that this is not systematic :-)

Yes, I could change MB/GB for MiB/GiB where it applies, if you are kind enough to check all pages where they are incorrect. I made this request once, and nobody answered, so I keep things as they are now :-(

In addition, a filesystem (ext4, e.g.) uses part of the managed disk capacity for its own usage, the same way as some pages of a book are reserved for its index; the user usable data amount is always less than the filesystem uses.

Further, in addition, at filesystem creation, some data (5% by default) is reserved for possible filesystem/system problem solving. You can reduce that amount, to zero, e.g., but you have to resort to the command line.

Login as the user 'root' using the same password as the webgui, and use the command 'tune2fs -m 0 /dev/<filesystem>', in your case

    tune2fs -m 0 /dev/md0

As an example, on a small disk:

/ # df -h /dev/md0 # shows size

Filesystem                Size      Used Available Use% Mounted on

/dev/md0                 46.3G     20.9G     23.0G  48% /mnt/md0

/ # tune2fs -m 0 /dev/md0 # remove reserved space

tune2fs 1.41.14 (22-Dec-2010)

Setting reserved blocks percentage to 0% (0 blocks)

/ # df -h /dev/md0 # show size again

Filesystem                Size      Used Available Use% Mounted on

/dev/md0                 46.3G     20.9G     25.4G  45% /mnt/md0

[Nemesio Garcia]

Thank you Joao! As a best practice, would you recommend leaving the 5% default for possible filesystem/system problem solving? I wouldn't want to decrease this amount if it can potentially cause issues in the future.

-NG

[Joao Cardoso]

On Monday, November 5, 2012 3:49:57 AM UTC, Nemesio Garcia wrote:

Thank you Joao! As a best practice, would you recommend leaving the 5% default for possible filesystem/system problem solving?

No.

For RC3 "no reservation" will be used. I considered using 1%, but it will be 0% (unless someone jumps with good arguments against)

There is an hypothetical usage of the reservation area on ext4 to prevent fragmentation on big files when the filesystem is near full. I'm not certain if this is real or myth.

[TJ]

When RC3 is released, and I upgrade (probably right away) will it automatically free up this 5% reservation, or should I free space using the command line before or after the upgrade? When I moved from RC1 to RC2 I erased all of my settings and just entered them manually, I would rather not do that this time: will RC3 update cleanly, or must a script be run?

Looking forward to the next RC!

Many thanks,

T.J.

[Joao Cardoso]

On Monday, November 5, 2012 2:04:54 PM UTC, TJ wrote:

When RC3 is released, and I upgrade (probably right away) will it automatically free up this 5% reservation,

No, only for new (webgui created) filesystems

 

or should I free space using the command line before or after the upgrade?

At any time. And you can reset the 5%, just  use 'tune2fs -m <integer percent> /dev/<device>'

 

When I moved from RC1 to RC2 I erased all of my settings and just entered them manually, I would rather not do that this time: will RC3 update cleanly, or must a script be run?

I do my bests to keep compatibility, but can't guarantee that, specially when there the user hand-edited configuration files.

 

Looking forward to the next RC!

It's not going to happen until I have positive feedback on the 3TB Disk Wizard fix posted under other 3TB topics :-O and all accepted/started issues are solved.

Joao

Many thanks,

T.J.