Short story: I shut down gracefully ESXi 5.0 to change some disks (move 4 and and 3).
When I power on again, no boot. (possibly a battery failure on my PERC 5/i as it appears to be weak now or a PSU problem - I changed both).
Partition table has been lost, as well as most ESXi partitions. VMFS data store on the same disk seems to be recoverable.
I saved (dd with linux live CD) all the disk to another one and copied again VMFS datastore to a new partition ; I reinstalled ESXi from scratch.
Achieved to mount again VMFS and copy back first virtual machine to main datastore.
Now the VM doesn't start, complaining about vmdk problem :
/vmfs/volumes/516da918-df9a2c66-694d-0015171dfbb4/Kaitan # ls -l
-rw------- 1 root root 1006698496 Apr 22 21:53 Kaitan-000001-delta.vmdk
-rw------- 1 root root 315 Apr 22 21:53 Kaitan-000001.vmdk
-rw------- 1 root root 6794838016 Apr 22 21:57 Kaitan-000002-delta.vmdk
-rw------- 1 root root 322 Apr 22 21:57 Kaitan-000002.vmdk
-rw------- 1 root root 19511967744 Apr 22 22:08 Kaitan-000003-delta.vmdk
-rw------- 1 root root 348 Apr 22 22:08 Kaitan-000003.vmdk
-rw------- 1 root root 28833 Apr 22 21:52 Kaitan-Snapshot1.vmsn
-rw------- 1 root root 28847 Apr 22 21:53 Kaitan-Snapshot2.vmsn
-rw------- 1 root root 2148825717 Apr 22 21:58 Kaitan-Snapshot3.vmsn
-rw------- 1 root root 32473405440 Apr 22 21:51 Kaitan-flat.vmdk
-rw------- 1 root root 8684 Apr 22 21:52 Kaitan.nvram
-rw------- 1 root root 615 Apr 22 21:51 Kaitan.vmdk
-rw-r--r-- 1 root root 1427 Apr 22 21:34 Kaitan.vmsd
-rwxr-xr-x 1 root root 3386 Apr 22 21:34 Kaitan.vmx
-rw-r--r-- 1 root root 3466 Apr 22 21:34 Kaitan.vmxf
-rw------- 1 root root 20480 Apr 22 21:53 Kaitan_1-000001-delta.vmdk
-rw------- 1 root root 319 Apr 22 21:53 Kaitan_1-000001.vmdk
-rw------- 1 root root 16797696 Apr 22 21:57 Kaitan_1-000002-delta.vmdk
-rw------- 1 root root 326 Apr 22 21:57 Kaitan_1-000002.vmdk
-rw------- 1 root root 2466271232 Apr 22 22:10 Kaitan_1-000003-delta.vmdk
-rw------- 1 root root 352 Apr 22 22:10 Kaitan_1-000003.vmdk
-rw------- 1 root root 9113610240 Apr 22 21:52 Kaitan_1-flat.vmdk
-rw------- 1 root root 591 Apr 22 21:52 Kaitan_1.vmdk
-rw-r--r-- 1 root root 160243 Apr 22 21:52 vmware-10.log
-rw-r--r-- 1 root root 408784 Apr 22 21:52 vmware-5.log
-rw-r--r-- 1 root root 165638 Apr 22 21:52 vmware-6.log
-rw-r--r-- 1 root root 159301 Apr 22 22:10 vmware-7.log
-rw-r--r-- 1 root root 555471 Apr 22 21:52 vmware-8.log
-rw-r--r-- 1 root root 159025 Apr 22 21:52 vmware-9.log
-rw-r--r-- 1 root root 160854 Apr 22 21:52 vmware.log
/vmfs/volumes/516da918-df9a2c66-694d-0015171dfbb4/Kaitan # vmkfstools -e Kaitan-000001.vmdk -v 10
DISKLIB-VMFS : "/vmfs/volumes/516da918-df9a2c66-694d-0015171dfbb4/Kaitan/Kaitan-000001-delta.vmdk" : open successful (14) size = 1006698496, hd = 1068279. Type 8
DISKLIB-DSCPTR: Opened [0]: "Kaitan-000001-delta.vmdk" (0xe)
DISKLIB-LINK : Opened '/vmfs/volumes/516da918-df9a2c66-694d-0015171dfbb4/Kaitan/Kaitan-000001.vmdk' (0xe): vmfsSparse, 63424620 sectors / 30.2 GB.
DISKLIB-VMFS : "/vmfs/volumes/516da918-df9a2c66-694d-0015171dfbb4/Kaitan/Kaitan-flat.vmdk" : open successful (14) size = 32473405440, hd = 871672. Type 3
DISKLIB-DSCPTR: Opened [0]: "Kaitan-flat.vmdk" (0xe)
DISKLIB-LINK : Opened '/vmfs/volumes/516da918-df9a2c66-694d-0015171dfbb4/Kaitan/Kaitan.vmdk' (0xe): vmfs, 63424620 sectors / 30.2 GB.
DISKLIB-CHAINESX : ChainESXOpenSubChain: numLinks = 2, numSubChains = 1
DISKLIB-CHAINESX : ChainESXOpenSubChainNode: can't create deltadisk node 7fdf066c-Kaitan-000001-delta.vmdk failed with error Invalid argument (0xbad0007, Bad parameter)
DISKLIB-CHAIN : "/vmfs/volumes/516da918-df9a2c66-694d-0015171dfbb4/Kaitan/Kaitan-000001.vmdk" : failed to open (Invalid argument).
DISKLIB-VMFS : "/vmfs/volumes/516da918-df9a2c66-694d-0015171dfbb4/Kaitan/Kaitan-000001-delta.vmdk" : closed.
DISKLIB-VMFS : "/vmfs/volumes/516da918-df9a2c66-694d-0015171dfbb4/Kaitan/Kaitan-flat.vmdk" : closed.
DISKLIB-LIB : Failed to open '/vmfs/volumes/516da918-df9a2c66-694d-0015171dfbb4/Kaitan/Kaitan-000001.vmdk' with flags 0xe Invalid argument (1441801).
DISKLIB-VMFS : "/vmfs/volumes/516da918-df9a2c66-694d-0015171dfbb4/Kaitan/Kaitan-000001-delta.vmdk" : open successful (12) size = 1006698496, hd = 888056. Type 8
DISKLIB-DSCPTR: Opened [0]: "Kaitan-000001-delta.vmdk" (0xc)
DISKLIB-LINK : Opened '/vmfs/volumes/516da918-df9a2c66-694d-0015171dfbb4/Kaitan/Kaitan-000001.vmdk' (0xc): vmfsSparse, 63424620 sectors / 30.2 GB.
DISKLIB-CHAINESX : ChainESXOpenSubChain: numLinks = 1, numSubChains = 1
DISKLIB-CHAINESX : ChainESXOpenSubChainNode: can't create deltadisk node 5d75e9f1-Kaitan-000001-delta.vmdk failed with error Invalid argument (0xbad0007, Bad parameter)
DISKLIB-CHAIN : "/vmfs/volumes/516da918-df9a2c66-694d-0015171dfbb4/Kaitan/Kaitan-000001.vmdk" : failed to open (Invalid argument).
DISKLIB-VMFS : "/vmfs/volumes/516da918-df9a2c66-694d-0015171dfbb4/Kaitan/Kaitan-000001-delta.vmdk" : closed.
DISKLIB-LIB : Failed to open '/vmfs/volumes/516da918-df9a2c66-694d-0015171dfbb4/Kaitan/Kaitan-000001.vmdk' with flags 0xc Invalid argument (1441801).
Failed to open disk link /vmfs/volumes/516da918-df9a2c66-694d-0015171dfbb4/Kaitan/Kaitan-000001.vmdk :Invalid argument (1441801)Disk chain is not consistent : Invalid argument (1441801)
AIOMGR-U : stat o=3 r=2 w=0 i=3 br=4096 bw=0
AIOMGR-S : stat o=3 r=9 w=0 i=0 br=147456 bw=0
/vmfs/volumes/516da918-df9a2c66-694d-0015171dfbb4/Kaitan # vmkfstools -x check Kaitan-000001.vmdk
Disk is error free
/vmfs/volumes/516da918-df9a2c66-694d-0015171dfbb4/Kaitan # vmkfstools -x check Kaitan.vmdk
Disk is error free
I'm running out of ideas, if someone can help...