Arch Linux

zacariaz

Member

From: Denmark

Registered: 2012-01-18

Posts: 539

[unsolved] BCache issues - Can't figure out what I'm doing wrong

My setup is as follows:

SSD on /dev/sda
HDD on /dev/sdb

I'm doing a EFI setup, so basically I need nothing more that an ESP and ROOT partition on /dev/sdb. I don't mind too much if the ESP partition is cached, but I suspect that could cause problems.

There's really no need to cache ESP, so my approach have been to only cache the root partition:

make-bcache -B /dev/sdb2 -C /dev/sda

Which seem to work.

After this everything seems to go wrong. I've tried several different approached and following the arch, gentoo and the official guide, but regardless I continually stumble.

Following the arch guide: https://wiki.archlinux.org/index.php/Bcache I run in to trouble already at step 3.

for i in /dev/sd*; do echo $i; echo $i > /sys/fs/bcache/register_quiet; done

But as I understand it, the fact that I can't write to register_quiet just mean that I don't need to. Well, that doesn't sound very sensible.

Apparently I can skip step 4., but even so I've tried different approaches as I said. However, no matter what I do, I end up missing /dev/bcache0, /sys/block/bcache0 or something similar, thus preventing me from continuing.

At this point I have no other options than to ask a few question here, and maybe get some advice.

1. In the case described, does sdb need to become backing device, or is it sensible to only make sdb2 (root) the backing device? [probably solved]

2. Assuming that sdb need to become the backing device, will EFI boot even be possible? [solved]

3. is btrfs a necessity, or is any file system in theory viable? [Suspect I don't need to use btrfs]

4. Whatever questions you may think I've left out. [still have issues]

Thanks and best regards.

Last edited by zacariaz (2013-08-19 15:15:12)

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I am a philosopher, of sorts, not a troll or an imbecile.
My apologies that this is not always obvious, despite my best efforts.

zacariaz

Member

From: Denmark

Registered: 2012-01-18

Posts: 539

Re: [unsolved] BCache issues - Can't figure out what I'm doing wrong

Just a small update.

I think I did it mostly right on the last try, however, I couldn't boot:

Attempting to register /dev/sda with bcache
ash: write error: Invalid argument
Attempting to register /dev/sdb with bcache
ash: write error: Invalid argument
Attempting to register /dev/sdb1 with bcache
ash: write error: Invalid argument
Attempting to register /dev/sdb2 with bcache
ash: write error: Invalid argument
Waiting 10 seconds for device /dev/bcache0 ...
ERROR: device '/dev/bcache0' not found. Skipping fsck
ERROR: Unable to find root device '/dev/bcache0'.

The only thing that comes to mind it that I made two boot entries with gummiboot, as I wasn't sure if I should define sdb2 or bcache0 as the root partition, but if that was the issue, I should at least get a boot menu I would think.

So that's how it is right now. I haven't got a clue what might be wrong.

Best regards.

---

I am a philosopher, of sorts, not a troll or an imbecile.
My apologies that this is not always obvious, despite my best efforts.

zacariaz

Member

From: Denmark

Registered: 2012-01-18

Posts: 539

Re: [unsolved] BCache issues - Can't figure out what I'm doing wrong

Status update:
I have officially given up.

Wednesday I may try one last time to get some help from at local community, but if they can't help, I'll just have to live with a rather slow computer untill I can pull some money together for an SSD to replace the unbelievable slow HDD.

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I am a philosopher, of sorts, not a troll or an imbecile.
My apologies that this is not always obvious, despite my best efforts.