Boston Linux & UNIX was originally founded in 1994 as part of The Boston Computer Society. We meet on the third Wednesday of each month at the Massachusetts Institute of Technology, in Building E51.

BLU Discuss list archive

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[Discuss] SysVinit vs. systemd

On Wed, Sep 17, 2014 at 1:10 PM, Richard Pieri <richard.pieri at> wrote:
> This may fail if you're using Multipath I/O.

Heh, Multipath i/o can break almost anything, but particularly when in
error cases.
Subtle interactions between bugs in different layers that aren't
*singly* a problem but ... are really hard to test for, or replicate.

I've had more failures made worse by Multipath than saved by it
(although not on Linux, and not a statistically significant quantity:
merely plural anecdotes so far; but both with OS-vendor MPio and
Storage-vendor MPio *sigh*).
    (E.g., in one case, OS & MPio bugs interacted when a card or
controller was bad - had we not had MPio, it would have been simple HW
crash to route away from and repair; with MP it behaved weirdly,
badly, and required debugging, as MPio masked the problem and
expressed it elsewhere.)

So MPio can be (mostly) good for a critical DB server's data storage,
i might use it again in similar max-uptime situation, but not as
ubiquitously; for other things, other more virtual forms of disk
access may be more resilient in reality. (And they're coming for our
DBs too.)

Bill Ricker
bill.n1vux at

BLU is a member of BostonUserGroups
BLU is a member of BostonUserGroups
We also thank MIT for the use of their facilities.

Valid HTML 4.01! Valid CSS!

Boston Linux & Unix /