[gentoo-user] Mysteriously dismounting partition

[Peter Humphrey]

Hello list,

I have a small rescue system in this box, using /dev/sda3 and /dev/sdb3 in a 
traditional partition layout. The disks are (supposedly) identical SSDs. All 
goes well when I boot the system, but by the time I come to write to sdb3 it's 
dismounted itself. It even dismounted itself once in the middle of syncing 
portage. Here's a snippet from fstab:

LABEL=RescueSys     /           ext4   relatime   1 1
LABEL=RescUsrBits   /usr-bits   ext4   relatime   1 2

I keep the portage tree under /usr-bits.

# dmesg | grep sdb3
[    1.753508]  sdb: sdb1 sdb2 sdb3 sdb4 < sdb5 sdb6 sdb7 sdb8 sdb9 >
[    4.833460] EXT4-fs (sdb3): mounted filesystem with ordered data mode. Opts: 
(null)
[  107.205918] EXT4-fs (sdb3): mounted filesystem with ordered data mode. Opts: 
(null)

You can see the successful mount at 4.8 s; the entry at 107 s is me mounting 
it again manually.

I've rewritten the partition label, and I've run a smartctl test which 
reported no faults found. I've also just reduced the speed of the chipset, 
which has three settings: good performance, better performance and turbo. It 
adopts the turbo setting by default and I've now set it to "better". It's too 
early yet to see if that will help.

What else can I try?

-- 
Rgds
Peter