Help with Fusion/corestorage repair

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Level 1

56 points

Help with Fusion/corestorage repair

My Fusion volume metadata got corrupted and I'm trying to repair it. I didn't have it backed up because a recent update to OS X broke support for my eSATA ExpressCard.

A botched attempt to use it by installing ubuntu seems to have corrupted it.

This is what it looked like when it was working:

[14-07-01@13:04][elvey@Computer-of-ME ~]$ diskutil corestorage list

CoreStorage logical volume groups (1 found)

|

+-- Logical Volume Group 147B7B2D-25FE-471F-BC2B-F40D401E5C00

=========================================================

Name: Fusion

Status: Online

Size: 620999999488 B (621.0 GB)

Free Space: 20889600 B (20.9 MB)

|

+-< Physical Volume B40D6368-C887-4918-87FC-B1EAC13C462A

| ----------------------------------------------------

| Index: 0

| Disk: disk1s4

| Status: Online

| Size: 492999999488 B (493.0 GB)

|

+-< Physical Volume 1452797C-9D64-49FB-9222-ED2B24DFDD1B

| ----------------------------------------------------

| Index: 1

| Disk: disk0s2

| Status: Online

| Size: 128000000000 B (128.0 GB)

|

+-> Logical Volume Family E2BC6303-B351-4DC5-8E44-BF127D15B1D6

----------------------------------------------------------

Encryption Status: Unlocked

Encryption Type: None

Conversion Status: NoConversion

Conversion Direction: -none-

Has Encrypted Extents: No

Fully Secure: No

Passphrase Required: No

|

+-> Logical Volume 5CC94C41-889F-4C93-9916-7A1B633CBBFA

---------------------------------------------------

Disk: disk2

Status: Online

Size (Total): 615074922496 B (615.1 GB)

Size (Converted): -none-

Revertible: No

LV Name: Macintosh HD

Volume Name: Macintosh HD

Content Hint: Apple_HFS

This is what it looks like now:

Computer-of-ME:~ newadmin$ diskutil corestorage list

CoreStorage logical volume groups (1 found)

|

+-- Logical Volume Group 147B7B2D-25FE-471F-BC2B-F40D401E5C00

=========================================================

Name: Fusion

Status: Offline

Size: 492484210688 B (492.5 GB)

Free Space: -none-

|

+-< Physical Volume B40D6368-C887-4918-87FC-B1EAC13C462A

| ----------------------------------------------------

| Index: 0

| Disk: disk1s4

| Status: Checking

| Size: 492484210688 B (492.5 GB)

|

+-< Physical Volume 1452797C-9D64-49FB-9222-ED2B24DFDD1B

----------------------------------------------------

(No properties)

Computer-of-ME:~ newadmin$ diskutil list

/dev/disk0

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *256.1 GB disk0

1: EFI 209.7 MB disk0s1

2: FFFFFFFF-FFFF-FFFF-FFFF-FFFFFFFFFFFF 128.0 GB disk0s2

3: Apple_HFS Boot OS X 134.2 MB disk0s3

4: Microsoft Basic Data 1.0 MB disk0s4

5: 0FC63DAF-8483-4772-8E79-3D69D8477DE4 121.3 GB disk0s5

6: Linux Swap 6.4 GB disk0s6

/dev/disk1

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *1.0 TB disk1

1: EFI 209.7 MB disk1s1

2: Apple_HFS HD 400.0 GB disk1s2

3: Apple_HFS scratch 100.0 GB disk1s3

4: Apple_CoreStorage 492.5 GB disk1s4

5: Apple_Boot Recovery HD 650.0 MB disk1s5

6: Apple_HFS Install OS X Mavericks 6.5 GB disk1s6

So, it looks to me like the underlying data is still fine: /dev/disk0s2 is still there and 128 GB; it's type is wacky. /dev/disk1s4 is still looking fine.
Those are/were the two underlying PV. But I'm looking at the diskutil manpage and I'm at a loss with respect to how to undo the damage. create | createLVG is destructive, so a no-no. I've backed up the remaining valuable data - the contents disk1s2. I'm thinking of experimenting; in preparation, I've backed up disk0s2 to a .dmg and will back up disk1s4 to a .dmg too. I have a copy of the partition tables of disk0 and disk1 from before the damage occurred, in the form of dd dumps of the first 5 blocks of the disks, thanks to:

/bin/dd if=/dev/rdisk0 of=/HD/Backups/GPTs/rdisk0.raw.gpt bs=512 count=5 conv=noerror
/bin/dd if=/dev/rdisk1 of=/HD/Backups/GPTs/rdisk1.raw.gpt bs=512 count=5 conv=noerror

Where is corestorage metadata actually stored? I'm wondering if the (incomplete TM) backups I do have, have backed it up.

Maybe the corestorage metadata is actually fine and its just the partition table that needs repair...

Message was edited by: MrElvey Add final line.

MacBook Pro (15-inch Early 2008), OS X Mountain Lion (10.8.2), SSD, USB, FireWire, external drives

Posted on Aug 11, 2014 11:50 PM

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Answer 1

Best reply

MrElvey Author

Level 1

56 points

Aug 12, 2014 4:38 PM in response to MrElvey

I guess I don't care if this this a destructive operation:
diskutil coreStorage create myLogicalVolGroup /dev/disk0s2 /dev/disk1s4

since my LVG still exists, and my PVs still exist (though the latter seems messed up); I do NOT need to run it.

I guess I DO need to run something like

diskutil coreStorage createLV 147B7B2D-25FE-471F-BC2B-F40D401E5C00 <type> <name> <size>

Where:

147B7B2D-25FE-471F-BC2B-F40D401E5C00 is my lvgUUID - parameter 1.

type is Journaled HFS+ ??? Journaled\ HFS+??? - parameter 2.

name is Phoenix - parameter3 - since it's rising from ashes!

size is 615074922496B - parameter 4 (better than "100%", I guess...

But first, I'd really like to know if createLV is a destructive operation!

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Answer 2

MrElvey Author

Level 1

56 points

Aug 12, 2014 5:00 PM in response to MrElvey

SOLVED!

All I needed to do was repair the partition table, changing the partition type back to Apple CoreStorage. Then the volume reappeared, and I backed it up.

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Answer 3

Jasc1977

Level 1

8 points

Feb 6, 2015 3:08 PM in response to MrElvey

Hi

How did you repair the partition table?

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Answer 4

NoiD™

Level 1

11 points

Mar 14, 2015 6:03 PM in response to Jasc1977

Yes, how!?

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Answer 5

justingb

Level 1

0 points

Jun 18, 2015 10:18 PM in response to MrElvey

I had a similar issue, in that my Fusion drive wouldn't boot. It'd hang after the login screen. When I rebooted into recovery mode (cmd+R), and ran disk utils, I got scary messages about the "The Fusion Drive is Missing a Disk", and a warning that repairing it would erase the data on the following drives... with an empty list. I bailed out of that because I didn't want to lose data. Running diskutil on the cmd line things didn't look right there either.

What ended up fixing it:

I rebooted from the internet (alt+cmd+R).

wait while the world spins (4-5 minutes)

open the terminal and run "diskutil cs list".

I made note of the drives (disk0s2 and disk1s2), and also noticed the status of one of the volumes was "Locked" not "Online"

I ran "fsck_cs -p disk0s2" and "fsck_cs -p disk1s2" - no errors were reported!

After this, the aforementioned status became "Online" (from "Locked")

I rebooted, logged in (success!) and immediately started a TimeMachine back up.

I believe that this fault in the Fusion drive started either with Bootcamp misbehaving (malware?) or a bad power-down (my wife and kids apparently fought over the power button before this started).

Hope this helps anyone else landing here from a web search. I know I was freaking out.

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