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AirPort showing different Time Capsule disk capacity than Time Machine

PatriotInvasion

PatriotInvasion

macrumors 68000
Original poster
Jul 18, 2010
1,645
1,061
Boston, MA
So I just secure erased my Time Capsule disk through AirPort Utility to set it up with my new iMac. After erasing the 1TB disk, AirPort said that the disk capacity is only 931GB even though the Time Machine preferences displayed 998GB available prior to me initiating the first backup.

Does anyone know why this discrepancy exists?

It should be noted that the previous backup on the Time Capsule disk from my old Mac took up about 68GB so is AirPort Utility just struggling to show the new capacity after the secure erase?:confused:

Please help!
 
I presume you're using OS X 10.6.x (Snow Leopard)?

The problem is that, the OS shows the 'total' value of the drive space in the Base10 calculated format (http://support.apple.com/kb/ts2419); while for some reason the 'AirPort' (AEBS, TimeCapsule) devices show the Binary System (Base2) calculated size of the drive space.

Because my 2TB time capsule in AirPort Utility shows it as 1.8TB, however OS X Finder and Time Machine see it as 2TB.
 
AppleNewton said:
I presume you're using OS X 10.6.x (Snow Leopard)?

The problem is that, the OS shows the 'total' value of the drive space in the Base10 calculated format (http://support.apple.com/kb/ts2419); while for some reason the 'AirPort' (AEBS, TimeCapsule) devices show the Binary System (Base2) calculated size of the drive space.

Because my 2TB time capsule in AirPort Utility shows it as 1.8TB, however OS X Finder and Time Machine see it as 2TB.
Click to expand...

I understand but this is not a discrepancy of 2 or 3GB's. My Time Machine preferences show that 930GB of 998GB is free while AirPort is saying just 862GB of 931GB is free on the same disk! It's off by over 60GB.

When I did a secure erase of the Time Capsule disk prior to initiating my first backup, AirPort seems to have not reset the max capacity of the drive back to 1TB (or 998GB). Any other ideas?

PS - Yes I am running the absolute latest version of everything - Snow Leopard included.
 
(2 ^ 30) * 930 = 998579896320
(2 ^ 30) * 931 = 999653638144
(2 ^ 30) * 932 = 1000727379968
 
PatriotInvasion said:
I understand but this is not a discrepancy of 2 or 3GB's. My Time Machine preferences show that 930GB of 998GB is free while AirPort is saying just 862GB of 931GB is free on the same disk! It's off by over 60GB.

When I did a secure erase of the Time Capsule disk prior to initiating my first backup, AirPort seems to have not reset the max capacity of the drive back to 1TB (or 998GB). Any other ideas?

PS - Yes I am running the absolute latest version of everything - Snow Leopard included.
Click to expand...


Well you didnt really mention that in your post other than saying its showing 931 in AirPort (which would be accurate) and 998 in Snow Leopard (~accurate).

There seems to be an issue with the TimeCapsule then, if nothing else.
I would connect it via ethernet and try another secure erase and a total restore of the TimeCapsule itself to eliminate any other possibility of error.

Then in finder navigate to the harddrive on the timecapsule to make sure no files are there.
 
AppleNewton said:
Well you didnt really mention that in your post other than saying its showing 931 in AirPort (which would be accurate) and 998 in Snow Leopard (~accurate).

There seems to be an issue with the TimeCapsule then, if nothing else.
I would connect it via ethernet and try another secure erase and a total restore of the TimeCapsule itself to eliminate any other possibility of error.

Then in finder navigate to the harddrive on the timecapsule to make sure no files are there.
Click to expand...

I was thinking of just doing a full reset of the Time Capsule (which will likely solve the problem), but I'll have to recreate my wireless network and everything just so the numbers match up.

There are no other files on the disk other than the sparsebundle that was created from the first backup. Strange...It's almost as if AirPort thinks the previous space available was the actual capacity of the disk even after I did a full erase of the disk.
 
It's not off by 60GB. The free space is off by about 4GB, according to the numbers you showed.
 
There could be a difference in the reporting of the size of files using HFS compression.
 
cube said:
It's not off by 60GB. The free space is off by about 4GB, according to the numbers you showed.
Click to expand...

What do you mean. This is what i said:

My Time Machine preferences show that 930GB of 998GB is free while AirPort is saying just 862GB of 931GB is free on the same disk! It's off by over 60GB.

930-862=68GB
 
They're both showing 93% full in their respective measuring units.

Computer manufacturers nowadays are starting to quote things in terms of billions of bytes, as opposed to gigabytes. A gigabyte is 2^30, or 1073741824 bytes. A billion bytes is 100000000 bytes. So one number is in billions of bytes, the other gigabytes.
 
willieva said:
They're both showing 93% full in their respective measuring units.

Computer manufacturers nowadays are starting to quote things in terms of billions of bytes, as opposed to gigabytes. A gigabyte is 2^30, or 1073741824 bytes. A billion bytes is 100000000 bytes. So one number is in billions of bytes, the other gigabytes.
Click to expand...

So are you saying that AirPort reporting 931GB of capacity for a 1TB Time Capsule is correct? I don't know what number was shown when I first set it up (may have been 931GB from the start, but not sure)...:confused::confused::confused:
 
PatriotInvasion said:
What do you mean. This is what i said:

My Time Machine preferences show that 930GB of 998GB is free while AirPort is saying just 862GB of 931GB is free on the same disk! It's off by over 60GB.

930-862=68GB
Click to expand...

The Airport label is wrong. It's not 862GB, it's 862GiB.
 
PatriotInvasion said:
So are you saying that AirPort reporting 931GB of capacity for a 1TB Time Capsule is correct? I don't know what number was shown when I first set it up (may have been 931GB from the start, but not sure)...:confused::confused::confused:
Click to expand...

I did the computation for you above.

Again, it should use GiB labels, not GB.

GiB was invented to avoid the misuse of GB.
 
What I'm saying is one system is calling a gigabyte 10^9 bytes. The other is saying a gigabyte is 2^30. If you do the math:
10^9 / 2^30 = 931 / 998

The ratio of sizes reported is equal to the ratio between 10^9 and 2^30.
 
cube said:
I did the computation for you above.

Again, it should use GiB labels, not GB.

GiB was invented to avoid the misuse of GB.
Click to expand...

Ok, so AirPort is showing the correct number despite the GB vs GiB designation??? So even if I completely reset the Time Capsule to it's factory settings, it will still report the same number and won't display the 998GB capacity number that Time Machine Preferences shows me during a backup?
 
PatriotInvasion said:
Ok, so AirPort is showing the correct number despite the GB vs GiB designation??? So even if I completely reset the Time Capsule to it's factory settings, it will still report the same number and won't display the 998GB capacity number that Time Machine Preferences shows me during a backup?
Click to expand...

Yes, the Airport number is correct, in gibibytes (2 ^ 30)

Snow leopard shows gigabytes (10 ^ 9)

That's the way they always display.

Previous versions of OSX showed mislabeled gibibytes, like the Airport.
 
cube said:
Yes, the Airport number is correct, in gibibytes (2 ^ 30)

Snow leopard shows gigabytes (10 ^ 9)

That's the way they always display.

Previous versions of OSX showed mislabeled gibibytes, like the Airport.
Click to expand...

Ok, fair enough. I appreciate everyone's help with this. Not sure why Apple wouldn't be consistent within applications that they created, but as long as everything is being reported correctly in their own way, I'm fine.:) Thanks again.
 
PatriotInvasion said:
Ok, fair enough. I appreciate everyone's help with this. Not sure why Apple wouldn't be consistent within applications that they created, but as long as everything is being reported correctly in their own way, I'm fine.:) Thanks again.
Click to expand...

It doesn't even mean that everything in Snow Leopard will use conventions consistently: legacy command-line programs, 3rd-party applications, etc.

You have to know how each piece of software is reporting. You can only be sure when a program uses KiB, MiB, GiB, TiB, etc.
 
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