Q: Total HD crash - how to get the files

" In short there is absolutely NO reason to not be backing up. Time Machine is a feature within OS X and all that is needed is an external HD."

it would have been nice to actually get some useful advice rather than telling off!

i've been using macs since the classic and have always managed to retrieve my files one way or another... in fact I managed to retrieve all my important stuff; I installed Yosemite on an external HD I had and managed to boot from it and collect my files that way... I tried repairing the disk from utilities but got a window saying "Disk Utility can't repair this disk. Back up as many files as possible and reformat the disk." ... I shut the computer down, unplugged the HD and restarted... the screen went straight to the Command R one... I opened up Utilities and attempted to erase the disk so I could reformat it... I then got this window "Disk Erase failed with the error. The given file system is not supported on Core Storage".... I restarted and tried again only to notice that my image file no longer appears, just the main HD (see attached pic) but it does show available space as 3TB so I guess it did erase of sorts;

I then plugged in the HD I loaded Yosemite on and restarted to see if the image appeared with Disk Utilities that way... no luck; I obviously can't reinstall a new OS as the install procedure can't find the iMac OS.

On the one hand I've managed to get the files (which was crucial) but I seemed to have made matter worse... how can I get the image file to appear again?

Here's the blurb I got when I ran a repair on "Macintosh HD" above (I'm trying to get the photos I took from the Errors and progress report from the iMac Disk as I think it has some important info)Utilitie:

Verifying and repairing partition map for “APPLE SSD SM128E Media”Checking prerequisitesChecking the partition listAdjusting partition map to fit whole disk as requiredChecking for an EFI system partitionChecking the EFI system partition’s sizeChecking the EFI system partition’s file systemChecking all HFS data partition loader spacesChecking booter partitionsChecking booter partition disk0s3Repairing file system.Checking Journaled HFS Plus volume.Checking extents overflow file.Checking catalog file.Checking multi-linked files.Checking catalog hierarchy.Checking extended attributes file.Checking volume bitmap.Checking volume information.Trimming unused blocks.The volume Boot OS X appears to be OK.File system check exit code is 0.Updating boot support partitions for the volume as required.Reviewing boot support loadersChecking Core Storage Physical Volume partitionsVerifying storage systemChecking volumedisk1s2: Scan for Volume Headersdisk0s2: Scan for Volume Headersdisk1s2: Scan for Disk Labelsdisk0s2: Scan for Disk LabelsLogical Volume Group 15F8E573-67DB-4940-B78D-F73391D8DCC1 spans 2 devicesdisk0s2+disk1s2: Scan for Metadata VolumeLogical Volume Group has a 4481 MB Metadata Volume with double redundancyStart scanning metadata for a valid checkpointLoad and verify Segment HeadersLoad and verify Checkpoint PayloadLoad and verify Transaction SegmentIncorporate 0 newer non-checkpoint transactionsLoad and verify Virtual Address TableLoad and verify Segment Usage TableLoad and verify Metadata SuperblockLoad and verify Logical Volumes B-TreesLogical Volume Group contains 0 Logical VolumesLoad and verify Freespace SummaryLoad and verify Block AccountingLoad and verify Live Virtual AddressesNewest transaction commit checkpoint is validLoad and verify Segment CleaningThe volume 15F8E573-67DB-4940-B78D-F73391D8DCC1 appears to be OKStorage system check exit code is 0.Repairing storage systemChecking volumedisk1s2: Scan for Volume Headersdisk0s2: Scan for Volume Headersdisk1s2: Scan for Disk Labelsdisk0s2: Scan for Disk LabelsLogical Volume Group 15F8E573-67DB-4940-B78D-F73391D8DCC1 spans 2 devicesdisk0s2+disk1s2: Scan for Metadata VolumeLogical Volume Group has a 4481 MB Metadata Volume with double redundancyStart scanning metadata for a valid checkpointLoad and verify Segment HeadersLoad and verify Checkpoint PayloadLoad and verify Transaction SegmentIncorporate 0 newer non-checkpoint transactionsLoad and verify Virtual Address TableLoad and verify Segment Usage TableLoad and verify Metadata SuperblockLoad and verify Logical Volumes B-TreesLogical Volume Group contains 0 Logical VolumesLoad and verify Freespace SummaryLoad and verify Block AccountingLoad and verify Live Virtual AddressesNewest transaction commit checkpoint is validLoad and verify Segment CleaningThe volume 15F8E573-67DB-4940-B78D-F73391D8DCC1 appears to be OKStorage system check exit code is 0.Updating Windows boot.ini files as requiredThe partition map appears to be OK

Verifying partition map for “APPLE SSD SM128E Media”Checking prerequisitesChecking the partition listChecking for an EFI system partitionChecking the EFI system partition’s sizeChecking the EFI system partition’s file systemChecking all HFS data partition loader spacesChecking booter partitionsChecking booter partition disk0s3Verifying file system.Checking Journaled HFS Plus volume.Checking extents overflow file.Checking catalog file.Checking multi-linked files.Checking catalog hierarchy.Checking extended attributes file.Checking volume bitmap.Checking volume information.The volume Boot OS X appears to be OK.File system check exit code is 0.Checking Core Storage Physical Volume partitionsVerifying storage systemChecking volumedisk1s2: Scan for Volume Headersdisk0s2: Scan for Volume Headersdisk1s2: Scan for Disk Labelsdisk0s2: Scan for Disk LabelsLogical Volume Group 15F8E573-67DB-4940-B78D-F73391D8DCC1 spans 2 devicesdisk0s2+disk1s2: Scan for Metadata VolumeLogical Volume Group has a 4481 MB Metadata Volume with double redundancyStart scanning metadata for a valid checkpointLoad and verify Segment HeadersLoad and verify Checkpoint PayloadLoad and verify Transaction SegmentIncorporate 0 newer non-checkpoint transactionsLoad and verify Virtual Address TableLoad and verify Segment Usage TableLoad and verify Metadata SuperblockLoad and verify Logical Volumes B-TreesLogical Volume Group contains 0 Logical VolumesLoad and verify Freespace SummaryLoad and verify Block AccountingLoad and verify Live Virtual AddressesNewest transaction commit checkpoint is validLoad and verify Segment CleaningThe volume 15F8E573-67DB-4940-B78D-F73391D8DCC1 appears to be OKStorage system check exit code is 0.The partition map appears to be OK

Verifying and repairing partition map for “APPLE HDD ST3000DM001 Media”Checking prerequisitesChecking the partition listAdjusting partition map to fit whole disk as requiredChecking for an EFI system partitionChecking the EFI system partition’s sizeChecking the EFI system partition’s file systemChecking all HFS data partition loader spacesChecking booter partitionsChecking booter partition disk1s3Repairing file system.Checking Journaled HFS Plus volume.Checking extents overflow file.Checking catalog file.Checking multi-linked files.Checking catalog hierarchy.Checking extended attributes file.Checking volume bitmap.Checking volume information.The volume Recovery HD appears to be OK.File system check exit code is 0.Updating boot support partitions for the volume as required.Reviewing boot support loadersChecking Core Storage Physical Volume partitionsVerifying storage systemChecking volumedisk1s2: Scan for Volume Headersdisk0s2: Scan for Volume Headersdisk1s2: Scan for Disk Labelsdisk0s2: Scan for Disk LabelsLogical Volume Group 15F8E573-67DB-4940-B78D-F73391D8DCC1 spans 2 devicesdisk0s2+disk1s2: Scan for Metadata VolumeLogical Volume Group has a 4481 MB Metadata Volume with double redundancyStart scanning metadata for a valid checkpointLoad and verify Segment HeadersLoad and verify Checkpoint PayloadLoad and verify Transaction SegmentIncorporate 0 newer non-checkpoint transactionsLoad and verify Virtual Address TableLoad and verify Segment Usage TableLoad and verify Metadata SuperblockLoad and verify Logical Volumes B-TreesLogical Volume Group contains 0 Logical VolumesLoad and verify Freespace SummaryLoad and verify Block AccountingLoad and verify Live Virtual AddressesNewest transaction commit checkpoint is validLoad and verify Segment CleaningThe volume 15F8E573-67DB-4940-B78D-F73391D8DCC1 appears to be OKStorage system check exit code is 0.Repairing storage systemChecking volumedisk1s2: Scan for Volume Headersdisk0s2: Scan for Volume Headersdisk1s2: Scan for Disk Labelsdisk0s2: Scan for Disk LabelsLogical Volume Group 15F8E573-67DB-4940-B78D-F73391D8DCC1 spans 2 devicesdisk0s2+disk1s2: Scan for Metadata VolumeLogical Volume Group has a 4481 MB Metadata Volume with double redundancyStart scanning metadata for a valid checkpointLoad and verify Segment HeadersLoad and verify Checkpoint PayloadLoad and verify Transaction SegmentIncorporate 0 newer non-checkpoint transactionsLoad and verify Virtual Address TableLoad and verify Segment Usage TableLoad and verify Metadata SuperblockLoad and verify Logical Volumes B-TreesLogical Volume Group contains 0 Logical VolumesLoad and verify Freespace SummaryLoad and verify Block AccountingLoad and verify Live Virtual AddressesNewest transaction commit checkpoint is validLoad and verify Segment CleaningThe volume 15F8E573-67DB-4940-B78D-F73391D8DCC1 appears to be OKStorage system check exit code is 0.Updating Windows boot.ini files as requiredThe partition map appears to be OK

Verifying partition map for “APPLE HDD ST3000DM001 Media”Checking prerequisitesChecking the partition listChecking for an EFI system partitionChecking the EFI system partition’s sizeChecking the EFI system partition’s file systemChecking all HFS data partition loader spacesChecking booter partitionsChecking booter partition disk1s3Verifying file system.Checking Journaled HFS Plus volume.Checking extents overflow file.Checking catalog file.Checking multi-linked files.Checking catalog hierarchy.Checking extended attributes file.Checking volume bitmap.Checking volume information.The volume Recovery HD appears to be OK.File system check exit code is 0.Checking Core Storage Physical Volume partitionsVerifying storage systemChecking volumedisk1s2: Scan for Volume Headersdisk0s2: Scan for Volume Headersdisk1s2: Scan for Disk Labelsdisk0s2: Scan for Disk LabelsLogical Volume Group 15F8E573-67DB-4940-B78D-F73391D8DCC1 spans 2 devicesdisk0s2+disk1s2: Scan for Metadata VolumeLogical Volume Group has a 4481 MB Metadata Volume with double redundancyStart scanning metadata for a valid checkpointLoad and verify Segment HeadersLoad and verify Checkpoint PayloadLoad and verify Transaction SegmentIncorporate 0 newer non-checkpoint transactionsLoad and verify Virtual Address TableLoad and verify Segment Usage TableLoad and verify Metadata SuperblockLoad and verify Logical Volumes B-TreesLogical Volume Group contains 0 Logical VolumesLoad and verify Freespace SummaryLoad and verify Block AccountingLoad and verify Live Virtual AddressesNewest transaction commit checkpoint is validLoad and verify Segment CleaningThe volume 15F8E573-67DB-4940-B78D-F73391D8DCC1 appears to be OKStorage system check exit code is 0.The partition map appears to be OK

here are some screen grabs I took of the error and progress report ran from Disk Utilities on the iMac rather than from the externaL HD ... I'm no expert but I  they hold some useful info think

2 more pics to come

had to split one of the pics in two even though it fell in the 2mb size and pixel ration limit

No, it wouldn't let me back up from time machine as my last back-up was 10.8 (I know I know)... but the thing is even if I did have a valid time machine backup there's no actual image file to download it to... effectively the OS I'm using on my external drive cannot see any other drive  - when I restart with just my iMac I get the option to reinstall the software but when it shows where I can install this software the main HD is missing  - the base system shows up but you can'y install anything on that.... I did a Terminal command to see if it showed up, it does, which is good, I hope but it no longer mounts. I guess that when I tried to erase the drive it did actually erase it even though a window popped up saying Disk Utilities was unable to do so... whatever happened corrupted the mount capability

here's another grab with what I think is the important bits adjusted to make it easier to read

remembered a couple of minor things before things went t*ts up ... I noticed that finder was starting to get really sluggish, lots of spinning beach balls even for simple things like moving a small file to trash or clicking from window to window.... I then opened Spotlight to look for something and noticed it had gone... I mean even the icon in system preferences had disappeared ... the normal spotlight keystroke bought up find file in open window mode... also noticed a lot of relevant comments from people saying Yosemite is experiencing problems with disk mounting across all platforms and types.

I managed to get the files I wanted by putting Yosemite onto an external HD and retrieving them from the mounted iMac HD file... since then the image file has disappeared completely so can't be mounted at all so it cannot be repaired or a new fresh install of Yosemite possible. I ran Tech Tool from a thumb drive and it showed a surface scan fail with 90 Bad Blocks (see pic) ... the SSD seemed to pass but it looks like the regular HD part is the one that's screwed... however I can't seem to repair it... is there anything else I can do? [incidentally, how to you boot into 'Recovery Partition?']