Gentoo Archives: gentoo-user

From: Mick <michaelkintzios@×××××.com>
To: gentoo-user@l.g.o
Subject: Re: [gentoo-user] External hard drive and idle activity
Date: Thu, 02 Jan 2020 16:23:32
Message-Id: 1971713.BVt7ZPEg4i@localhost
In Reply to: Re: [gentoo-user] External hard drive and idle activity by Rich Freeman
1 On Thursday, 2 January 2020 14:43:58 GMT Rich Freeman wrote:
2
3
4 > Out of curiosity, what model drive is it? Is it by chance an SMR /
5 > archive drive?
6
7 Good catch! I hadn't thought of this - the Linux kernel will need to have
8 DM_ZONED enabled I think, for the OS to manager the shingled writes
9 sequentially, but I don't have this enabled here because AFAIK I have no such
10 drives in my possession.
11
12
13 > Due to the limitations on how those write data out I
14 > could see them implementing an internal filesystem that journals
15 > incoming data and then writes it back out after the fact.
16
17 SMR drives which implement a 'device managed' write mechanism, will use their
18 own firmware to control data storage. The OS would not be aware of anything
19 being different to a conventional drive.
20
21
22 > If so then
23 > that might happen even after the kernel thinks it is unmounted.
24 > However, such a drive firmware would probably use a journal that
25 > ensures data is safe even if power is cut mid-operation. The drive
26 > isn't supposed to report that a write is completed until it is
27 > durable.
28
29 Which I take it to mean the drive would not be unmounted by the OS until it is
30 safe to do so and for all intends and purposes it will also be safe to be
31 powered down thereafter. I would think this would be within seconds of
32 successfully unmounting it. Spinning for 30 minutes or more after it is
33 unmounted sounds excessive to me, if it is only being spun by the firmware for
34 flushing its journal buffers. I have a conventional USB drive (WD passport)
35 which is always spinning whether it is being written to or not.
36 --
37 Regards,
38
39 Mick

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Re: [gentoo-user] External hard drive and idle activity Rich Freeman <rich0@g.o>