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

I'm struggling with two new 4TB drives in an early-2008 Mac Pro. The first drive I installed, formatted using Disk Utility, and copied 4TB of data on to it with no problem

I only later noticed that it was an LVG, so the second drive I formatted after booting from the original Leopard install disc that came with the machine. However the resulting GUID Partition Table volume seems very slow to write to – when I tried to copy a couple of TB on to it the OS told me it was going to take hundreds of days to copy. The first new drive, set up a logical volume group, is fine.

However, what I don't know is why a disc formatted as a logical volume is a problem. What are the disadvantages? I only need it as storage - it will never be connected to a PC, used as RAID or as a boot volume. Can I leave it as a logical volume without worry?

sam410 wrote:

...However, what I don't know is why a disc formatted as a logical volume is a problem. What are the disadvantages? I only need it as storage - it will never be connected to a PC, used as RAID or as a boot volume. Can I leave it as a logical volume without worry?

I believe you can. I ran into the same issue and found that as long as I don't plan to erase the contents of a partition with DU, the drive behaves normally. Oddly, the partitioning scheme looks normal if viewed from a Snow Leopard or Lion boot partition with Disk Utility and can be worked on (e.g., erased) without difficulty.

Thanks, glad to hear it's working for you. However I've now reformatted the slow drive under Mountain Lion as an LVG, but it is still very slow!

To copy a 1.25GB folder with 300-odd jpg files takes 25s on one drive but 25 minutes on the other. Could that be down to format issues, or could the drive be faulty?

I don't think it's the disparity in formatting because all of my drives were originally formatted in Lion or Snow Leopard and they've worked properly when booted from Mountain Lion or Mavericks (hooray for four drive bays!).

I'd be more suspicious of the drive itself. Using Activity Monitor for measuring file transfer rate, what happens when you copy a large file (I use a Debian virtual machine because it's big enough to get a sense of the speed over time) to each 4TB drive?

BTW, I assume SMART status is OK for both drives (Disk Utility won't show SMART for the LVG, but System Information will).

Thank you so much! This kept me from calling Western Digital like an idiot and saying "the replacement drive you sent me (which was 2.5 TB to replace my 2 TB HD, for whatever reason) doesn't work!"

I'll just put this in for anyone like me who, for one reason or another, won't use the install DVD method. Do at your own risk. The instructions are only valid for a newly inserted blank hard drive that has had one partition created on it. Don't hold me responsible, I've tested them on mine a few times. As I said, at your own risk.

• In Disk Utility, unmount the erroneous volume
• Open Terminal
• sudo su - (it's the minus sign, and then enter your password)
• diskutil cs list
• in the list, find the Physical Volume branch under the Logical Volume Group diskutil created for you - that would be a "Disk: diskXsY" kind of line e.g. disk5s2.
• Back in Disk Utility, click on all of your drives one by one, then on Info, and verify that the disk identifier of each is NOT diskX above. You don't want to wipe another drive by mistake.
• go back to Terminal and in the following line, replace VolumeName and diskX. Note you don't need the sY part, e.g. for disk5s2 you will be using /dev/disk5 only.
• diskutil eraseDisk JHFS+ VolumeName /dev/diskX - cross your fingers and hit return.

I have figured out a solution to this issue. Go to the terminal and enter the following.

diskutil cs delete “Put Your Logical Volume Group UUID Here”

Ex. 8DD219E1-AA47-4F4C-A9DF-72BE79143B43

You can get your UUID from the About This Mac-More Info-System Report-Storage

Make sure to select the proper drive and you want the UUID for the Logical Volume GROUP.

It worked for me:

Disk Description : ST3000DM001-1CH166 Media
Total Capacity : 3 TB (3,000,592,982,016 Bytes)

Connection Bus : SATA
Write Status : Read/Write

Connection Type : Internal
S.M.A.R.T. Status : Verified

Connection ID : "Bay 3"
Partition Map Scheme : GUID Partition Table 🙂

Hi Jake10e,

I'm not sure if you ever found a solution to your problems, but I'm here to help you! and this is the absolute "Simplified Answers" that you and/or anyone in this situation.

First thing first, remove all "extra" external and internal hard drives from you mac if possible. (leave your main Mac OS X of course!)

Second. Leave only the affected HHD in question that has "Logical Volume Group". Therefore, this will eliminate all the confusion and mistake that you might see.

1, Go to Finder and right click on the affected hhd and select "Get Info"

2, Once the info window opens up, go down to the bottom right corner and click the padlock key to enter your password to unlock it, and keep it unlock at all time.

3, Now, Open the terminal and type exactly as follows: (WITHOUT THE ">>>>>") I use 5 greater arrow signs to indicate terminal input only!

>>>>> diskutil cs list (Return Key) (There are 2 groups of Numbers you need to pay attention to and those are "Logical Volume" and "Logical Volume Group")

you should see something like this "Logical Volume 123FE123-1234-123E-B5EF-ED9EB123B0CE"

Now, type in exactly as follows and of course remember to replace your own "Logical Volume 123FE123-1234-123E-B5EF-ED9EB123B0CE":

>>>>> diskutil coreStorage deleteVolume 123FE123-1234-123E-B5EF-ED9EB123B0CE (Return Key) (remember to type in only your "123FE123-1234-123E-B5EF-ED9EB123B0CE" DO NOT TYPE IN THE WORD "Logical Volume". This will delete and unmount the "Logical Volume" only.

Now, you will continue with deleting the "Logical Volume Group" as follows:

>>>>> diskutil coreStorage delete A12345B5-C123-456C-789F-9E123A2A1234 (Return Key) (remember to type in only your "A12345B5-C123-456C-789F-9E123A2A1234" DO NOT TYPE IN THE WORD "Logical Volume Group" This will remove all info's and return your hhd back to its virgin state.

Now, open up the disk utilities app and you will see its virgin state and all its options to like "First Aid, Erase, Partition, RAID, Restore" back again.

Note: The Most Important Thing To Remember is "Make Sure That The Permission Padlock in UNLOCK At All Time"

Lock it back when you're all done.

Good Luck!

justinfromfort collins, your last post was very helpful, thank you !

Thank you justinfromfort collins. Your solution help to fix the Logical Volume Bug for my WD 3TB Green HDD. Thanks again!

Hi This is my 1st post so be prepared. I went round this a different way by erasing in firewire disk Target mode between two macs and adding guid table and then raiding.

cheers ben

The commands are:

diskutil cs list

diskutil cs deleteVolume <Logical Volume UDID>

diskutil cs delete <logical volume group UDID>

Thanks for the command lines SnipperJS. My DVD drive is dead and will not boot from the install disk.

This fixed it 🙂

The commands are:

diskutil cs list

diskutil cs deleteVolume <Logical Volume UDID>

diskutil cs delete <logical volume group UDID>

I'm on 10.9.5 and this set of commands brought my new 3TB drive back from Core Storage/Logical Volume Group **** - and then I successfully repartitioned it into 4 volumes using the same procedure that had previously gotten me into trouble using Disk Utility. Seems to be working fine and I'm currently cloning another drive to it.

So is the bug hit-and-miss intermittent? Am I in for trouble down the road? Did it get fixed in Yosemite or El Cap?

Only the Mac Pro silver towers, last issued in 2012 can have this problem (unless you dismantle your iMac to install a huge drive inside).

Core Storage Logical Volume group is EXACTLY what you would like if the next command is to encrypt the whole drive or create a Fusion Drive. So MacBook Pro owners are not unhappy.

This has been an issue since 10.8.4 and has not been changed, despite the major reworking of the GUI for 10.11 ElCapitan.

So Don't hold your breath on this being fixed.

YES - had this Logical Volume Group format as well on a MacPro Early 2008 inserting a new Toshiba 3 GB drive and hitting the wrong tab.

There is a brute force way in Terminal to zap the GPT:

(you need to do that in an administrative account, so you can sudo, having all the powers for one command - be carful and check typing twice, so there are no extraneous spaces and such)

sudo gpt destroy disk3

replace disk3 with whatever disk you need to zap the GPT.

The disk number can be found in Disk Utility if you select the respective disk.

After that you have an unformatted disk.

(gpt can also create GPT tables, and partitions, see man gpt in Terminal)

Hope that helps