Gentoo Archives: gentoo-user

From: Michael Mol <mikemol@×××××.com>
To: gentoo-user@l.g.o
Subject: Re: [gentoo-user] How can I power disk off?
Date: Fri, 07 Oct 2011 01:15:21
Message-Id: CA+czFiDMe2+JMaZoRoSHR56+L0zUxqPaft1fHp=OZS+KpSc6jA@mail.gmail.com
In Reply to: Re: [gentoo-user] How can I power disk off? by Mark Knecht
1 On Oct 6, 2011 9:06 PM, "Mark Knecht" <markknecht@×××××.com> wrote:
2 >
3 > On Thu, Oct 6, 2011 at 1:28 PM, Michael Mol <mikemol@×××××.com> wrote:
4 > > On Thu, Oct 6, 2011 at 4:21 PM, Mark Knecht <markknecht@×××××.com>
5 wrote:
6 > >> On Thu, Oct 6, 2011 at 1:03 PM, Paul Hartman
7 > >> My worry was that if the mdraid daemon saw one drive gone - either
8 > >> when starting to spin down or when one spins up slowly - and if mdraid
9 > >> didn't understand that all this stuff was taking place intentionally
10 > >> then it might mark that drive as having failed.
11 > >
12 > > Does mdraid even have an awareness of timeouts, or does it leave that
13 > > to lower drivers? I think the latter condition is more likely.
14 > >
15 > > I suspect, though, that if your disk fails to spin up reasonably
16 > > quickly, it's already failed.
17 > >
18 >
19 > In general I agree. However drives that are designed for RAID have a
20 > feature known as Time Limited Error Recovery (TLER) which supposedly
21 > guarantees that they'll get the drive back to responding fast enough
22 > to not have it marked as failed in the RAID array:
23 >
24 > http://en.wikipedia.org/wiki/Time-Limited_Error_Recovery
25 >
26 > When I built my first RAID I bought some WD 1TB green drives, built
27 > the RAID and immediately had drives failing because they didn't have
28 > this sort of feature. I replaced them with RAID Edition drives that
29 > have the TLER feature and have never had a problem since. (Well, I
30 > actually bought all new drives and kept the six 1TB drives which I'd
31 > mostly used up for other things like external eSATA backup drives,
32 > etc...)
33 >
34 > Anyway, I'm possibly over sensitized to this sort of timing problem
35 > specifically in a RAID which is why I asked the question of Paul in
36 > the first place.
37
38 My first RAID was with three Seagate economy 1.5TB drives in RAID 5, shortly
39 followed by three 1TB WD black drives in RAID 0. I never had the problems
40 you describe, though I rebuit the RAID5 several times as I was figuring
41 things out. (the 3TB RAID0 was for some heavy duty scratch space.)

Replies

Subject Author
Re: [gentoo-user] How can I power disk off? Mark Knecht <markknecht@×××××.com>