[kwlug-disc] Was cronjob / btrfs scrup [Was: Re: What is all this about systemd?]

[B.S.]

Hmmm. <cough> ... did you just say ... presentation? (-:

Thanks for the post / heads up / good points.

NFS root file system on a NAS? ... have to ponder on that. (I know 
little of NFS / doesn't seem popular on home networks.)

Perhaps a usb video doohickey bears investigating? [I poked not long ago 
- it doesn't appear that usb video doohickey's are particularly Linux 
friendly, at least at the moment.]

You bring up a good topic - robust network storage at home. Or 
something. Ties in with OwnCloud, for that matter? Hard to do a 
presentation on, I suspect - deep dives on things like zfs have been 
done (by Lori IIRC?), hard not to have to do a deep dive then have no 
time for use cases such as you describe.

Just poking about the little I just did on btrfs and vbox, one drowns. 
Scrubbing, checksums, various ways to get to similar but nuanced 
differences, ...


On 14-10-30 01:24 PM, Chris Irwin wrote:
> On Thu, Oct 30, 2014 at 12:54 PM, B.S. <bs27975 at yahoo.ca> wrote:
>
>> I suppose there'd be a performance hit with btrfs checksummed over
>> snapshots, but presumably also less complexity, let alone more timely alert
>> of any hardware issue. (?)
>>
>
> You don't want to store your VMs on BTRFS. They actually specifically say
> not to, as you'll cause significant fragmentation. Currently their defrag
> method can cause problems with snapshots, I believe.
>
> You can disable COW for your VM directory, which will solve fragmentation.
> However, it will also negate the benefits of BTRFS in the first place
> (checksums, snapshots, etc). I've still got my "legacy" LVM disk for VM
> storage because I can just snapshot the whole filesystem, and either cp,
> rsync, or dump the contents.
>
> To meet my goal of as few extra filesystems as possible, I'm trying to
> convert my VMs to have NFS root filesystems, which can be exported from my
> NAS, and thus benefit from the BTRFS there. I haven't had success yet,
> though.
>
>
>> In poking about, it seemed that such a mirror becomes self-healing. A spot
>> goes bad, checksum fails, things get recopied. Interesting.
>>
>
> That's why I'm using BTRFS -- checksums and recovery. It's also why I run a
> weekly scrub before my snapshot and backup.
>
> ZFS is another option, possibly more stable. However, I wanted to stay
> in-tree, especially since my server doesn't have a display connector, so
> I'll be blind-booting USB media if I ever have a fail to boot situation.
> (or looking for a spare graphics adapter, I guess).
>
>
>
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