ISCSI, RAID, NTFS headache

[ithelp]

I hope somebody has encountered and successfully resolved the issue I am about to detail below. Thank you for finding the time and energy to keep all this going.

I have a dell E520 with the following specs
FreeNAS-8.3.1-RC1-x64 (r13329)
Platform Intel(R) Pentium(R) 4 CPU 3.00GHz
Memory 3822MB

I put two 3TB drives, configured them in mirror setup (software). Then setup the ISCSI as a device extent. Then I proceeded to initiate a connection from a win 2008 R2 server. After establishing connection I formatted the new drive NTFS and shared it. Then I moved some important files having no other backup. The moving went great. I think the next day I initiated another connection from another win 2008 r2 to the scsi and I think I was able to see the ntfs formated drive. A couple of days later the scsi became unavailable and I get errors that the drive is unreadable and needs to be formated. the volume health is reported healthy from freenas gui. Now if i connect one server to freenas i am asked to format the drive and don't want to do it. I don't want to loose the date. Is there a way for me to repair/recover/restore the connection or the data? I would appreciate specific commands and steps if possible.

Thank you

 

[cyberjock]

Ok, 2 things before I discuss the issue you posted about:

1. If you are using ZFS with that little RAM, you are crazy, and data loss was almost inevitable. There's a reason why the manual says to have at least 6GB of RAM. Performance and stability. If the system is unstable and keeps panicing you'd eventually experience data loss. Anything from 1 or 2 files to the entire zpool.
2. I'm not sure why you'd use a release candidate when the release version is out. I don't recommend people use release candidates on systems that store any important data. Release candidates have been known to eat people's data permanently because of bugs.

Now onto your problem...

iSCSI devices should only be mounted on one system. If the first Win 2008 R2 server had the iSCSI device mounted(even if you weren't using it) and you connected the second Win 2008 R2 server to the same iSCSI device at the same time....boom.. instant and almost permanent data loss.

Even if that isn't your issue, the solution is still the same.

You need to find some data recovery tools and run them on the "unformatted" drive. I recommend r-studio since I've used it before and had good luck with it twice. But don't expect to get a lot of data recovered. If the file system is so corrupted that it can't even mount you have major corruption.

 

[jgreco]

Slight correction:

iSCSI devices can potentially be mounted on many systems. However, an NTFS filesystem should only be mounted on a single system, as it is not a cluster-aware filesystem. If one host writes some stuff to disk and the other host never notices and then tries to write something else in the same place, craziness results.

Those of us who use iSCSI with virtualization platforms such as VMware vSphere use cluster-aware filesystems like VMFS. A change made on one host is safely written to the datastore and other hosts will become aware of the change; potential collisions are resolved through clever technical design of the filesystem, and sync writes to the disk. A VMware datastore on an iSCSI device might easily be mounted on dozens of hosts.

That having been said, mounting the same NTFS filesystem on multiple hosts is a massive fail. Take cyberjock's advice. I would even suggest making a backup copy of the iSCSI disk prior to trying anything, but that may be a bit of a challenge to do correctly and usefully at this point.

 

[ithelp]

Thank you for your reply. I am not using ZFS but UFS. I got R-studio and it can see the files even restore them with the correct size. However, if I try to open one it fails with error messages - usually a corrupt file. Any suggestions?

 

[jgreco]

ZFS vs UFS is irrelevant for this discussion. The NAS device is operating as a SAN and providing block level storage access, just like if you took an external USB drive and hooked it up to a PC. If you take that USB drive and were able to hook it up to two PC's at the same time (you can't), you'd have the same exact types of problems if you tried to put an NTFS filesystem on it.