Mirrored Hard Drive being Swallowed by "My-Guess-is-as-Good-as-Yours"
 

I have a 20 gig mirrored drive (10 gig each) formatted with OS X, and it says I've but 100 mb left on it. I have examined EVERY visible and invisible (with Cocktail's aid) file on it, and all of the files take up fewer than 4 gigs. It should be reading about 5 gigs available, but it's spitting out the 100 mb number. Someone please tell me what and, possibly, where these phantom files are on my mirrored drive! I wanted to update to OS X.2.8, but the Software Update said I hadn't sufficient space. As it unfolds, I, in fact, do NOT have enough, as the majority of my HD is ensconced by demon files!

THANK YOU

Sir Virgil II

Try using OmniDiskSweeper to see what is taking the disk space:
http://www.omnigroup.com/applications/omnidisksweeper/

Muchas gracias, vaquero. Just the program I was looking for. Omnigroup has always released exemplary quality software.

Merci

H.R.H. Virgil

But could it be a problem with the "mirroring"? Or an insatiable virtual memory requisite?

Lord Virgil II

You'll know that when you find out what's taking up the space.

You do know that using two 10 GB drives mirrored leaves you with 10 GB of space, and not 20 GB, as you implied in your first post, yes?

Thank you. Of course I know that. It's a twenty gig drive total, but split into two halves to make a mirrored drive. Thus, ten gig on each half.

Dr. Virgil

Quick Update
 

I just ran OmniDiskSweeper on the mirrored drive and it says that but 3 gigs are being used, yet when you select Get Info on the mirrored, it reads fewer than 100 mb left. WTF.

Mrs. Virgil

Sorry.. when you say mirrored, you mean you have one 20G drive, split into two 10G partitions, and everything that happens on the first 10G partition is automatically mirrored onto the second 10G partition?

When you first open ODS, there's a Drive List, and it tells you that there is X amount free space and Y amount used on a Z amount total sized disk. Are both partitions showing up or is only 1 disk being shown here?

Then, when you select the partition that you're having trouble with and "sweep" it, you should be able to see where the largest uses of space on the drive are.. anything looking out of the ordinary?

Answer to question 1:
Correct.

Answers to questions 2 & 3:
The mirrored drive is showing up here as one disk. But it reads that it has but 97 mb remaining, a different number from what the "Get Info." will give (205 mb). When I sweep the mirrored drive, it reads that I've used but 3 gb, a different reading from the "Y" variable, which read 9.4 gb.


I should be having about 6.5 gb left on this hard drive, not 97 (or 205) mb.

Virgil, Ph.D.

Hmmm.. I wonder if swap space is being mirrored as well and never gets removed as needed. I don't know why the Finder seems to be incorrectly interpreting disk space. What does 'df' tell you? How are you mirroring these partitions, via Raid?

This is what a quick "df" command tells me:

Filesystem 512-blocks Used Avail Capacity Mounted on
/dev/disk3 20063160 19662024 200512 98% /

¡Ké lástima!

Virgil, Psy.D.

Odd.. the OS seems to think that there's really isn't much disk space left. Is there some particular reason that you're mirroring the drive?

So that if something were to happen to the drive, I would have multiple backups.
I have iMsafe installed, but that shouldn't afford any problems analogous to this.

one cannot RAID partitions from the same disk, in any form.

Umm.. but.. if something happens to the drive, you're mirroring on the same drive, so.. umm.. if somthing happens to the drive...

Ah, ok. I know virtually nothing about RAID and have no need to know anything about it. Makes sense not to be able to RAID along partitions as the whole point seems to be to mirror along separate disks for failover..

So what suggest you I do? I am thinking about reformatting the aggregate drive. It's two drives together as one, that's why I mirrored it. If something were to happen to one mirror, then the other would have the integral office files.

Correct.

Virgil, Esq.

I understand your basic reasoning behind the mirroring.. but if you're going to mirror a drive for immediate failover, I it would be much safer to do it onto a secondary (internal/external) hard drive. If your partitioned hard drive fails, then most likely the partition that you're backing up to fails as well, earning you a net result of 'Oh.. for the love of fudge!!'. I suppose backing up to a partition could have it's uses, but I wouldn't put too much hope into it..
Of course none of this saves you from a fire.. but that's another story.

i am thoroughly confused. is there RAID involved here, or not? is there greater than one physical disk drive, or not? if this "mirror" is just a half partition of one physical disk, then what is doing the "mirroring"? there is no evidence of >1 drive or partition, even, in your df output.

The office files are, in fact, backed up on another hard drive regularly. One can never be too sure.
Any other suggestions, anyone? I'm thinking about formatting entire HD and upgrading to Panther (non-server edition), but I am still wary of Panther due to its share of problems.

It could be a deleted file that is still being held open by a process.

Now I have not tested this on HFS+, but on all other unixes I have dealt with, if you open a file and write 100MB to it, du and df will both see that space taken up.

If a process opens the file (for read or write) and then you delete the file, the 'directory entry' goes away but the file still has a 'link' count of 1 due to the reading process, so the space is not freed. Once the process quits, the link count drops to 0 and the OS will turf the file.

In such cases, while the process is still holding the file open, 'df' should report the correct amount of used disk space, but du will not as it checks files that have directory entries.

You may want to try a reboot and see if you then have recovered your space (I think it may be too hard to locate and kill a process that is doing this, but that would be the better option).

I have seen questions on deleting swap files (/var/vm/swapfile0,1...), and would think this would apply to them as well.

As I said, I have not had a chance to test this on HFS+, maybe someone with some more time on their hands can do it.....

The swapfile0 located in /var/vm is just 87 mb. There is but one swapfile in that directory. Thank you for your advice.

The swapfile thing was just an example. It could be any file that is held open.

Have you tried a reboot?

For future reference: RAID (in pictures).

I don't think it's applicable to the situation under discussion here, though.

I have rebooted quite a few times now, for various reasons. And to what avail? None noticeable. I don't understand why it cannot list what is eating my space.

Well, it may take a while, but could you post the output from the following commands?
(I know we have seen the df before, but things may have changed.)

The other thing that is a possibility is the mounting of a file system onto a directory that already contains stuff. When that happens, du cannot see the files contained in the directory as they are 'covered' by the new mount, but df still knows about them.

Any mounted filesystems?

I'm at home right now. I just wanted to say gracias for all of your altruism. I'll try that command tomorrow when I'm at the office.

Merci

Miss Virgil