Is possible recovering a deleted file, after clearing the snapshots?

[Javierus]

I have a FreeNAS 9.2.1 box that works perfectly with 6 3TB HDDs in RaidZ2. No problems with the box: hardware side runs smooth.

All the stuff on it was moved to another server 4 months ago, and today I intended to use it as a backup storage for the other server.
However, I forgot one VM was still using the FreeNAS as iSCSI server.
So, I deleted 4 datasets full of nothing useful, and 4 of the extents on the dataset that was holding the Extents for the iSCSI service. Left 2 of them, just in case.
Then I wiped all the snapshots, to recover the space.
To make it worse, made a new dataset, called "BACKUP", and started copying there the 2 extents I had left on the old dataset.

And, ofcourse, then found I had dumped one critical file, one used as Extent for iSCSI, wich was used as safe storage for another computer.

No, there are no backups, because this was supposedly just a backup.

Using zdb history -il shows me the txg prior to the deletion of datasets and snapshots, but trying to mount it with

Code:

zpool import -T 123456 -fFX -o readonly=on -R /mnt TANK

fails:

Code:

cannot import 'TANK': one or more devices is currently unavailable

if I try -nfFX, says nothing, but -fFX fails.

At this point I guess it's game over, but just wanted to ask, in case there is something I could try
One additional thing: one of the six disks is down; as it's a Z2, all is working fine anyway.

Any help or desperate idea??

 

[cyberjock]

You generally can't mount from arbitrary txgs. You'll need to look at the superblock to see what is/isn't available. ;)

BUT, if your datasets/zvols had multiple TB of data, you'll almost certainly be unable to rollback.

 

[Javierus]

cyberjock, thanks for your help.
The zpool had 10TB, and the lost file had 2TB.

This was part of the output of zdb history -li DATOS (where DATOS is my zpool name).
The snapshots prior to 8:31 have what I need. I've tried some of these txgs... Might you point me to any place I could learn about the superblocks, other than google "zfs superblock"?

Theanks in advance :)

Code:

2016-04-12.08:30:54 zfs destroy DATOS/iSCSI@auto-20160411.2000-6d
2016-04-12.08:30:54 [txg:13478368] destroy DATOS/iSCSI@auto-20160412.0100-1m (102842)
2016-04-12.08:30:57 ioctl destroy_snaps
    input:
        snaps:
            DATOS/iSCSI@auto-20160412.0100-1m

2016-04-12.08:30:57 zfs destroy DATOS/iSCSI@auto-20160412.0100-1m
2016-04-12.08:30:57 [txg:13478370] destroy DATOS/iSCSI@auto-20160412.0800-6d (102864)
2016-04-12.08:31:05 ioctl destroy_snaps
    input:
        snaps:
            DATOS/iSCSI@auto-20160412.0800-6d

2016-04-12.08:31:05 zfs destroy DATOS/iSCSI@auto-20160412.0800-6d
2016-04-12.08:31:05 [txg:13478372] snapshot DATOS/iSCSI@auto-20160412.0831-6d (102886)
2016-04-12.08:31:13 ioctl snapshot
    input:
        snaps:
            DATOS/iSCSI@auto-20160412.0831-6d
        props:

2016-04-12.08:31:13 zfs snapshot -r DATOS/iSCSI@auto-20160412.0831-6d
2016-04-12.08:37:35 [txg:13478434] destroy DATOS/iSCSI@auto-20160412.0831-6d (102886)
2016-04-12.08:37:43 ioctl destroy_snaps
    input:
        snaps:
            DATOS/iSCSI@auto-20160412.0831-6d