Re: [gentoo-user] Re: Emerge --sync source

[Rich Freeman]

On Thu, Mar 7, 2019 at 9:29 AM Grant Edwards <grant.b.edwards@×××××.com> wrote:
>
> On 2019-03-07, Mick <michaelkintzios@×××××.com> wrote:
>
> > I can think of 3 things, but more learned M/L contributors may add to these:
> >
> > 1. The SATA connection has come loose.  With time and movement it can come
> > (slightly) adrift.  Pushing it back in fully fixes this problem - also see No.
> > 2 below.
> >
> > 2. The physical connector's contacts are beginning to oxidise.  Reseat the
> > SATA cable connectors both on the drive and any ribbons on the MoBo.  This
> > usualy cleans any oxidisation.
> >
> > 3. The AHCI driver is deploying energy saving measures (aka. Aggressive Link
> > Power Management - ALPM).  Check the output of:
> >
> >  cat /sys/class/scsi_host/host*/link_power_management_policy
> >
> > If it doesn't say 'max_performance' you'll need to revisit your BIOS settings
> > and also PCIEASPM settings in the kernel.
> >
> > 4. Finally, there is a chance the PSU is playing up.
>
> Perhaps it's already been mentioned, but failing RAM can cause all
> sorts failures that might appear to be failing disks, failing network
> cards, failing video cards whatever.  I'd run memtest86 for at least
> 12 hours just to make sure...
>

Failing RAM or failing power certainly can cause all manner of
filesystem and other corruption.  I've seen it firsthand and cleaning
up from it is a total mess (usually best to restore from backup).  I
would definitely start with a memory test - if the motherboard is good
then you can work outwards from there.

From what I've heard SSDs can have bizarre failure modes since they
interpose a logical layer between the physical storage media and the
rest of the system.  They're doing wear-leveling and so on behind the
scenes, which means that if something goes wrong all kinds of bizarre
problems can occur.

I've also experienced a spinning hard drive exhibit lots of data
corruption issues due to a faulty SATA interface (not sure where in
the interface it - chipset, port, or cable).  ZFS saved me there with
detection and resolution of errors, and when I moved the drive to a
different HBA it worked fine after a scrub.  I'd never seen anything
like it before but it really made me appreciate ZFS (btrfs should have
also worked) - I don't think mdadm would have had any way to resolve
these errors easily, though maybe if I used a hex editor to figure out
which drive was the bad one I might have been able to move it, wipe
it, then re-add it to the mirror pair and let it rebuild.  With ZFS I
just got an email complaining about errors from zed and it just kept
beating back the hordes until I fixed the connection.  I forget if it
dropped the drive or not - I didn't have any spares but if I did I
suspect it would have swapped it in after enough problems.

-- 
Rich