disc utility inconsistent free space

+I can understand if "get info" is unable to see certain files due to permissions, but why should disk utility report different values via startup and OS?+

It shouldn't. They all get their information from the volume header, so permissions don't matter. I suspect this is an issue with the SSD firmware. Have you asked OCZ tech support?

Not addressing the different sizes but you do not have enough space for a BC partition, think 32g minimum + 10% of your drive left empty, around 40g is what you need, and don't have.

1.5G?

Good luck with that.

Let me know how practice matches theory, I've used XP on a 4G partition, frankly it was awful, but maybe your experience will be better.

jonlee016 wrote:
Hey guys,
My hard drive reports inconsistent free space using various methods.

When I click "get info" on my Macintosh HD, it reports 18GB free.
When I use disk utility, it reports 7GB free.

Disk Utility will show two different "free" readings, depending on where you look.

Sounds odd, but they're for different purposes. The larger figure, which the Finder and other things will use, is the total free space available.

The second is the amount of free space available for a new partition. It's shown when you select the top line for the drive, click the Partition tab, then select a partition, the "Available" amount may be smaller.

This is because partitions, unlike folders, must occupy contiguous space on a disk. The data on your OSX partition is scattered over it, not all nicely packed together. That's normal, as you add, update, and delete files, not every nook and cranny is used again immediately.

But whether there's 7 GB free or 18, that probably isn't enough to be adding a partition; it's probably too little for OSX to operate well. There's no "hard and fast" rule, but you should always have at least 10 GB or 10% of your OSX drive free; many folks say 15% or more.

You could back up your drive (on two different HDs, to be safe), reformat it to 2 parttions, then restore the backup. But it's going to be very tight, and you'll likely have performance problems because of it.

Try to delete anything you don't need, and/or offload stuff you don't use often and delete it.

+Does OSX really read volume data from the same header in all methods?+

I can't say that I know the internals of the Finder or Disk Utility, but since they give instant answers they must be getting their information from somewhere, and I don't know where that would be other than the volume header or the partition table.

I have SSD's and I've never seen a discrepancy among the various free-space estimates. On the other hand, I've never used Boot Camp or created an NTFS partition, so maybe it has something to do with that.

Linc Davis wrote:
+Does OSX really read volume data from the same header in all methods?+

I can't say that I know the internals of the Finder or Disk Utility, but since they give instant answers they must be getting their information from somewhere, and I don't know where that would be other than the volume header or the partition table.

I have SSD's and I've never seen a discrepancy among the various free-space estimates. On the other hand, I've never used Boot Camp or created an NTFS partition, so maybe it has something to do with that.

You'll see some discrepancy on any drive that's been in use for very long, unless it's been defragged or restored recently.

Click the top line for your OSX disk, select Partition, then click your OSX partition in the center panel and note what it shows as available.

Then click the OSX partition and see what it shows at the bottom.

Message was edited by: Pondini

Curiously, using df through the terminal gives me 55.57GB free space if my math
is correct (116559584/2/1024/1024) which is different from the 59.68GB reported in "get info".

It's a side issue with regard to the Disk Utility reports, but there's a reason for the above discrepancy. Snow Leopard's units were changed - Snow Leopard uses base 10 rather than base 2 for its disk space reports, so that 1 GB now represents 10 ^9^ bytes rather than 2 ^30^ bytes as it did on previous systems. All sizes reported in GB will be about 7% larger when using base 10 units compared to base 2 units.

Terminal's df command can report "human readable" sizes in either base 2 (using the -h option) or base 10 (using the -H option). For my current boot volume, both Get Info and Disk Utility show 168.82 GB free. This matches the base 10 result obtained from Terminal's df -H command:

$ df -H /
Filesystem Size Used Avail Capacity Mounted on
/dev/disk5s2 321G 152G 169G 48% /
.
whereas in base 2 units:
$ df -h /
Filesystem Size Used Avail Capacity Mounted on
/dev/disk5s2 299Gi 141Gi 157Gi 48% /

jonlee016 wrote:
. . .
My remaining issue, however, is that while the disk utility used from boot DVD reports 12GB available for partitioning, the value AFTER entering the OS is 7GB available for partitioning. This suggests that I could make a bigger partition if done from startup as opposed to after entering OSX. Maybe this is done on purpose?

I don't follow. Are you saying you see different figures from Disk Utility on your Mac than the version on your Snow Leopard Install disc, in the same place?

• Click the top line for the drive, then the Partition tab, then the partition in the blue box.
  
• Click the partition name in the sidebar.
  

I guess my 60GB SSD is still a bit small to be adding a second partition though.

Sure sounds like it.

I'd expect them to be somewhat different, as some system swap and temporary files will be different; they're deleted when you boot up, then rebuilt as necessary.

But that shouldn't be a large difference, unless you've been using a whole lot of apps so OSX has had to do a lot of paging.

You are using a Snow Leopard disc, right?