Disk Utility defaulted to Logical Volume Group format for new 4TB HDD and won't let me change to GUID. Is that a problem?

Alley_Cat wrote:

I wonder if DIsk Utility logs drive formatting anywhere?

AC

Here we go, from DiskUtility.log:

So looks as though I formatted it with 10.8.5 😕

AC

Can the dead drive be salavaged and reformatted using 10.9 or earlier ML installations or on a Windows system?

• 10.6.0 or 10.6.3 "Full Retail" DVD from its Utilities on DVD, or even older DVD;

• any intervening version from its Recovery_HD (on DVD or thumb drive) through 10.8.3;

• any intervening version on a Hard Drive through 10.8.3;

• also in an External enclosure under the troubled versions {10.8.4, 10.8.5, 10.9.0} (provided the enclosure has large drive support);

• 10.9.0 = Not as an Internal drive;

Windows System not sure, but likley.

N.B.> I hesitate to recommend Windows since So Many Windows users TRASH their Mac OS X Volume using Windows Tools to re-configure a Multi-OS Volume.

I dunno how you managed to do that.

¿ Did you simply Partition, rather than Erase?

Yes, I would not have erased it.

Have I been doing it wrong all these years 😮

AC

Have I been doing it wrong all these years 😮

...and now you are the only peron around who has a new large drive that works under 10.8.4 through 10.9.0.

It would have been an unformatted drive so I would never have thought to use the erase option.

Basically following:

from this or similar:

http://manuals.info.apple.com/MANUALS/0/MA173/en_US/MacPro_HardDrive_DIY.pdf

I've always assumed it does some kind of 'quick format' .

AC

¿ You read the directions ?

Probably quite some time ago....

Grant Bennet-Alder wrote:

Have I been doing it wrong all these years 😮

...and now you are the only peron around who has a new large drive that works under 10.8.4 through 10.9.0.

Just to see if it's reproducible:

New 4TB WD black added (FW drives and bay 4 removed):

3 partitions 2x320GB and the rest:

So If I hear you correctly, you are saying an additional work-around is:

DO NOT CLICK "ERASE" or your drive will be unusable!

Use only the "Partition" tab.

Follow the promts to create the number of partitions desired.

Done.

I think you are suggesting no one does this normally, but yes, for both previously unformatted drives I simply clicked on the drive and Partition rather than Erase in Disk Utility. I have no idea what would happen with a previously formatted drive but couldn't see any point erasing a new drive whcih most of mine are when I partition them.

Just wanted to test that I could Partition another new 4TB drive via DiskUtility in 10.8.5.

I don't think I've ever used the Erase option to be honest - I might if I was giving a drive away but once I partition and format a drive I rarely re-partition it or give it away anyway.

Does using Erase perform a low-level format of some kind that would take all day on a large drive?

Tried making a couple of partitions this time just to see it wasn't unique to a single partition option.

Also diskutil cs list still give a 'No CoreStorage logical volume groups found'

AC

I am more like you. Use the Partition tab primarily and only lately ever used Erase.

You have to choose "Secure Erase" to write zero to the entire drive, otherwise it is a quick zero, tests all the blocks though where partition tables will be locked into place and insures a backup volume information block exists and works, so the first and last (400,000? more?) sectors are w/o any write/read error.

Interesting that DU behaves differently as I thought some folks had tried at least to partition 4TB into 2 x 2TB to see if they could get around the issue, but never a success story at a 3TB or larger partition.

Does using Erase perform a low-level format of some kind that would take all day on a large drive?

In the dim distant past, it would indeed re-write the block number headers and all the formatting information. Modern drives often use a mechanical device to discern rotational position, so only the data blocks are re-written when you do the equivalent of "format".

The time required to re-write all the data blocks can easily stretch into hours. That is why skeptical old f@rts like me assume the factory did not take the time to do it properly and insist that "whenever a drive is re-purposed" is an ideal time to re-write everything.

Disk Utility does not erase more than the Directory area when you say Erase with no additonal options selected. To get Disk Utility to do overwrite the entire data area, you have to use Security Erase option, and move it off the default at least one click to get it to write one pass of Zeroes over the entire data area.

Grant Bennet-Alder wrote:

Does using Erase perform a low-level format of some kind that would take all day on a large drive?

In the dim distant past, it would indeed re-write the block number headers and all the formatting information. Modern drives often use a mechanical device to discern rotational position, so only the data blocks are re-written when you do the equivalent of "format".

The time required to re-write all the data blocks can easily stretch into hours. That is why skeptical old f@rts like me assume the factory did not take the time to do it properly and insist that "whenever a drive is re-purposed" is an ideal time to re-write everything.

Disk Utility does not erase more than the Directory area when you say Erase with no additonal options selected. To get Disk Utility to do overwrite the entire data area, you have to use Security Erase option, and move it off the default at least one click to get it to write one pass of Zeroes over the entire data area.

Thanks for the explanation. On Windows formatting used to take an eternity unless you used a quick format technique, though I always used to use the slower option. SInce moving to Macs in 2006 and with drive sizes increasing significantly I have always assumed teh partition option just did a quick format/partitioning and never really looked for teh full format which I assumed would take many hours or even days to complete on drives over 1TB.

Seems this technique does currently work in 10.8.5 for drivesover 2TB using Partition - I wonder if the supplemental update a few weeks ago added a fix quietly?

Here's the solution that worked for me. I booted into MacOS X 10.7 from an external disk, launched Disk Utility from there and noticed right away that disks that were seen as Logical Volume Groups under 10.9 were seen as GUID volumes under MacOS X 10.7. The names of the disks were correct and everything looked as I would have expected. Even the disk names were back to their originals. They had been changed to the name of one of the partitions when I erased the partition and changed that name under 10.9.

So I used Disk Utility under 7.0 to erase and re-partition one of the disks. These options were not available in Disk Utility under 10.9.

Rebooting into 10.9, I note that Disk Utility there shows this disk and its partition as GUID so that seems to be a way to recover from this situation.

I am currently in the process of carefully shuffling data around so that I can erase a re-partition the other affected volumes.

To speculate, I would guess that Apple changed Disk Utility to accommodate fusion disks and, in doing so, screwed things up. I have logged a report of this at bugreport.apple.com.