* Bricked-ish Bcache Backing Disk
@ 2017-08-28 4:00 Shaun S
2017-08-28 5:21 ` Pavel Goran
0 siblings, 1 reply; 2+ messages in thread
From: Shaun S @ 2017-08-28 4:00 UTC (permalink / raw)
To: linux-bcache
I need to recover a file from a bcache disk that won't mount, the
underlying fs is btrfs. I'd like to read the btrfs partition directly
by skipping the bcache data with dd skip=#, but I need to know how
much data to skip. Can anyone help me out?
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: Bricked-ish Bcache Backing Disk
2017-08-28 4:00 Bricked-ish Bcache Backing Disk Shaun S
@ 2017-08-28 5:21 ` Pavel Goran
0 siblings, 0 replies; 2+ messages in thread
From: Pavel Goran @ 2017-08-28 5:21 UTC (permalink / raw)
To: Shaun S
Hello Shaun,
Monday, August 28, 2017, 11:00:02 AM, you wrote:
> I need to recover a file from a bcache disk that won't mount, the
> underlying fs is btrfs. I'd like to read the btrfs partition directly
> by skipping the bcache data with dd skip=#, but I need to know how
> much data to skip. Can anyone help me out?
Bcache tools include a program called bcache-super-show, it shows various
values from the cache or backing device superblock. In particular, there is
the "dev.data.first_sector" value which is what you want.
In my case, it shows:
dev.data.first_sector 16
Which means that the underlying data begins from 16-sector (8-kilobyte) offset
of the backing device.
Pavel Goran
^ permalink raw reply [flat|nested] 2+ messages in thread
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