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From: William Kenworthy <billk@iinet.net.au>
To: gentoo-user@lists.gentoo.org
Subject: Re: [gentoo-user] [OT] SMR drives (WAS: cryptsetup close and device in use when it is not)
Date: Sat, 31 Jul 2021 11:14:23 +0800	[thread overview]
Message-ID: <7a8c52c3-4c96-89ac-ace0-6eb4b8f1401f@iinet.net.au> (raw)
In-Reply-To: <CAGfcS_=8sjEe60KEuVsoqEyj5TbK177H0vf2fY3yQp370h+VFw@mail.gmail.com>


On 30/7/21 10:29 pm, Rich Freeman wrote:
> On Fri, Jul 30, 2021 at 1:14 AM William Kenworthy <billk@iinet.net.au> wrote:
>> 2. btrfs scrub (a couple of days)
>>
> Was this a read-only scrub, or did this involve repair (such as after
> losing a disk/etc)?
>
> My understanding of SMR is that it is supposed to perform identically
> to CMR for reads.  If you've just recently done a bunch of writes I
> could see there being some slowdown due to garbage collection (the
> drive has a CMR cache which gets written out to the SMR regions), but
> other than that I'd think that reads would perform normally.
>
> Now, writes are a whole different matter and SMR is going to perform
> terribly unless it is a host-managed drive (which the consumer drives
> aren't), and the filesystem is SMR-aware.  I'm not aware of anything
> FOSS but in theory a log-based filesystem should do just fine on
> host-managed SMR, or at least as well as it would do on CMR (log-based
> filesystems tend to get fragmented, which is a problem on non-SSDs
> unless the application isn't prone to fragmentation in the first
> place, such as for logs).
>
> Honestly I feel like the whole SMR thing is a missed opportunity,
> mainly because manufacturers decided to use it as a way to save a few
> bucks instead of as a new technology that can be embraced as long as
> you understand its benefits and limitations.  One thing I don't get is
> why it is showing up on all sorts of smaller drives.  I'd think the
> main application would be for large drives - maybe a drive that is
> 14TB as CMR could have been formatted as 20TB as SMR for the same
> price, and somebody could make that trade-off if it was worth it for
> the application.  Using it on smaller drives where are more likely to
> be general-purpose is just going to cause issues for consumers who
> have no idea what they're getting into, particularly since the changes
> were sneaked into the product line.  Somebody really needs to lose
> their job over this...
>
No, it was a normal scrub (read only is an option) - I did the scrub
hoping it wasn't necessary but aware that crash halting the OS while
doing a backup while the system was generating ooops after an upgrade
wasn't going to guarantee a clean shutdown. Ive just kicked off a scrub
-r and am getting 41Mb/s speed via the status check (its a usb3 on the
disk side, and usb2 on the PC - configuration: driver=usb-storage
maxpower=30mA speed=480Mbit/s). I will monitor for a couple of hours and
see what happens then swap to a standard scrub and compare the read rate.

rattus ~ # date && btrfs scrub status
/run/media/wdk/cae17311-19ca-4e3c-b476-304e02c50694
Sat 31 Jul 2021 10:55:43 AWST
UUID:             cae17311-19ca-4e3c-b476-304e02c50694
Scrub started:    Sat Jul 31 10:52:07 2021
Status:           running
Duration:         0:03:35
Time left:        22:30:40
ETA:              Sun Aug  1 09:26:23 2021
Total to scrub:   3.23TiB
Bytes scrubbed:   8.75GiB  (0.26%)
Rate:             41.69MiB/s

Error summary:    no errors found


lsusb: Bus 003 Device 007: ID 0bc2:331a Seagate RSS LLC Desktop HDD 5TB
(ST5000DM000)

(seagate lists it as a 5Tb drive managed SMR)

It was sold as a USB3 4Tb desktop expansion drive, fdisk -l shows "Disk
/dev/sde: 3.64 TiB, 4000787029504 bytes, 7814037167 sectors" and Seagate
is calling it 5Tb - marketing!

BillK





  parent reply	other threads:[~2021-07-31  3:15 UTC|newest]

Thread overview: 64+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-14  4:50 [gentoo-user] cryptsetup close and device in use when it is not Dale
2021-06-15 13:48 ` Ramon Fischer
2021-06-15 14:21   ` Dale
2021-06-15 14:52     ` Jack
2021-06-15 15:26       ` Dale
2021-06-15 19:04         ` Ramon Fischer
2021-06-21  4:18         ` Dale
2021-06-21  4:49           ` Dale
2021-06-21  5:41             ` Dale
2021-06-21  5:59               ` Dale
2021-06-28  3:35                 ` Dale
2021-07-05  3:19                   ` Dale
2021-07-06 18:40                     ` Ramon Fischer
2021-07-06 19:43                       ` Dale
2021-07-07 14:48                       ` Dr Rainer Woitok
2021-07-07 18:08                         ` Dale
2021-07-08  8:20                           ` Ramon Fischer
2021-07-12  8:31                             ` Dale
2021-07-12 13:14                               ` Ramon Fischer
2021-08-02 13:33                                 ` Dale
2021-08-09 13:38                                   ` Ramon Fischer
2021-09-19 11:55                                     ` Dale
2021-07-25 20:29                           ` Frank Steinmetzger
2021-07-25 23:10                             ` Dale
2021-07-26 21:00                               ` Frank Steinmetzger
2021-07-26 22:48                                 ` Dale
2021-07-29 16:46                                 ` Wols Lists
2021-07-29 20:55                                   ` [gentoo-user] [OT] SMR drives (WAS: cryptsetup close and device in use when it is not) Frank Steinmetzger
2021-07-29 21:31                                     ` Frank Steinmetzger
2021-07-30 12:48                                       ` Frank Steinmetzger
2021-07-30  5:14                                     ` William Kenworthy
2021-07-30 14:29                                       ` Rich Freeman
2021-07-30 16:50                                         ` antlists
2021-07-30 18:38                                           ` Rich Freeman
2021-07-31  3:14                                         ` William Kenworthy [this message]
2021-07-31  3:50                                           ` Wols Lists
2021-07-31  4:58                                             ` William Kenworthy
2021-07-31 12:12                                               ` Rich Freeman
2021-08-01  0:41                                                 ` Frank Steinmetzger
2021-08-01  0:56                                                   ` Rich Freeman
2021-07-31 16:38                                               ` antlists
2021-08-01  0:50                                               ` Frank Steinmetzger
2021-08-01  3:36                                                 ` William Kenworthy
2021-08-01  3:46                                                   ` William Kenworthy
2021-08-01 21:38                                                     ` Frank Steinmetzger
2021-08-02  5:38                                                       ` William Kenworthy
2021-08-02 21:52                                                         ` Frank Steinmetzger
2021-08-02 23:10                                                           ` William Kenworthy
2021-08-03  8:18                                                             ` Frank Steinmetzger
2021-08-05 20:40                                                               ` Frank Steinmetzger
2021-08-06  7:22                                                                 ` William Kenworthy
2021-08-01 21:55                                                   ` Frank Steinmetzger
2021-08-02  6:12                                                     ` William Kenworthy
2021-08-02 22:03                                                       ` Frank Steinmetzger
2021-08-02 23:35                                                         ` William Kenworthy
2021-08-01  3:41                                                 ` William Kenworthy
2021-08-01 21:41                                                   ` Frank Steinmetzger
2021-07-31 12:21                                             ` Rich Freeman
2021-07-31 12:59                                               ` William Kenworthy
2021-07-31 13:30                                                 ` Rich Freeman
2021-08-01  3:05                                                   ` William Kenworthy
2021-08-01 11:37                                                     ` Rich Freeman
2021-07-31  5:23                                           ` William Kenworthy
2021-06-15 17:48     ` [gentoo-user] Re: cryptsetup close and device in use when it is not Remy Blank

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