From: Pavel Goran <via-bcache@pvgoran.name>
To: Shaun S <linux-bcache@vger.kernel.org>
Subject: Re: Bricked-ish Bcache Backing Disk
Date: Mon, 28 Aug 2017 12:21:46 +0700 [thread overview]
Message-ID: <7152087.20170828122146@pvgoran.name> (raw)
In-Reply-To: <CAHnpKQXSHaEL3n5pJNAduM1J=+2SFZEz_h2a3kOzM7MhDvtWwQ@mail.gmail.com>
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
prev parent reply other threads:[~2017-08-28 5:26 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-28 4:00 Bricked-ish Bcache Backing Disk Shaun S
2017-08-28 5:21 ` Pavel Goran [this message]
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