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Date:      Thu, 26 Feb 2015 06:30:41 -0500
From:      grarpamp <grarpamp@gmail.com>
To:        freebsd-fs@freebsd.org
Cc:        developer@open-zfs.org, zfs-devel@freebsd.org
Subject:   Zoned Commands ZBC/ZAC, Shingled SMR drives, ZFS
Message-ID:  <CAD2Ti2_smoPJ=%2B0PbHMi00i_hCGydzr3X2Twh7myqu3h6GnSNg@mail.gmail.com>

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> On Wed, 25 Feb 2015 16:19 Shehbaz Jaffer <shehbazjaffer007@gmail.com>:
> I thought proposal was to implement FreeBSD - ZFS on SMR Drives.

That's right. Same as Linux and EXT4 were both adapted for SMR.

> 1. How will we emulate SMR Drives on QEMU?

Given that you can request drive samples for development from
feldman@seagate , I'd think the QEMU question is left to QEMU.

> 2. How should we go about using open source SMR Drives and use
> these in FreeBSD?

Thanks for your interest, there are good people here to collaborate
development with. Also, the overall OS agnostic home for ZFS is at
http://www.open-zfs.org/
Have a look there as well. They have a pretty active ZFS list. There
are enough links below to get people started. Are you still affiliated
with NetApp as suggested by the sig in your first email?



> On Wed, 25 Feb 2015 Mark Felder <feld@freebsd.org>:
> Do I understand the scope of this correctly:

I'll try based on limited reading, refer to the links and video for
authoritative answers.

> - SMR drives are the future for increasing drive capacity

So far, given spindle vs SSD applications, likely yes. Seagate just
released 8TB top of their "Archive" line for $280. Western Digital
Hitachi has a 10TB model in the queue.

SMR seems to be something FreeBSD and ZFS would want to incorporate
in order to further compete in the storage space.

> - SMR drives are terrible at random IO

Haven't found any benchmarks yet. There may be some in these
presentations or over in Linux land. I think only random writes are
currently performance caveated if you are not SMR host aware. These
drives present three types of management and have huge caches. The
host aware and filesystem mods are meant to address speed. Drives
will do 150MB/s r/w avg.

> - There is work in Linux to detect these SMR drives

Yes, in their storage stacks. They work as a dumb non-optimized LBA
device without it.

>  and alter ZFS' behavior

Linux is enhancing EXT4. The presentations in the links hope to
enhance ZFS as well. ZFS's copy on write seems well suited to SMR.



I don't have anything to do with or know anything, just didn't
initially see any FreeBSD + SMR + ZFS references out there.
Have fun.


========= Newly added links

ZFS Host-Aware_SMR
https://www.youtube.com/watch?v=b1yqjV8qemU

SMR Modifications to EXT4 (and other generic file systems)
http://www.spinics.net/lists/linux-ext4/msg46868.html
http://www.spinics.net/lists/linux-scsi/msg81950.html

Linux has been adding support since their 3.18 kernel onwards...
https://git.kernel.org/cgit/linux/kernel/git/hare/scsi-devel.git/log/?h=zac.v2
https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/commit/?id=7a14c1c3319608154da8712e4174d56ffb2f7b8d
https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/commit/?id=9162c6579bf90b3f5ddb7e3a6c6fa946c1b4cbeb
https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/commit/?id=f9ca5ab832e7ac5bc2b6fe0e82ad46d536f436f9

Drive specs
http://www.seagate.com/www-content/product-content/hdd-fam/seagate-archive-hdd/en-us/docs/archive-hdd-dS1834-3-1411us.pdf
http://www.seagate.com/www-content/product-content/hdd-fam/seagate-archive-hdd/en-us/docs/100757960c.pdf
http://www.hgst.com/science-of-storage/next-generation-data-centers/10tb-smr-helioseal-hdd

ZBC/ZAC specs
http://www.t10.org/members/w_zbc-.htm
http://www.t13.org/Documents/MinutesDefault.aspx?keyword=di537

========= Previous links for reference

ZFS Host-Aware_SMR
http://open-zfs.org/w/images/2/2a/Host-Aware_SMR-Tim_Feldman.pdf
http://www.youtube.com/watch?v=b1yqjV8qemU

ZFS on SMR Drives: Enabling Shingled Magnetic Recording (SMR) for Enterprises
http://storageconference.us/2014/Presentations/Novak.pdf

ZBC device manipulation library
https://github.com/hgst/libzbc

Seagate SMR Friendly File System - EXT4
https://github.com/Seagate/SMR_FS-EXT4

Initial ZAC support
http://www.spinics.net/lists/linux-scsi/msg81545.html
ZAC/ZBC Update
http://www.spinics.net/lists/linux-scsi/msg80161.html

libzbc - The Linux Foundation
http://events.linuxfoundation.org/sites/events/files/slides/SMR-LinuxConUSA-2014.pdf

Panel: Shingled Disk Drives - File System Vs. Autonomous Block Device / SFS
http://storageconference.us/2014/Presentations/Panel4.Bandic.pdf
http://storageconference.us/2014/Presentations/Panel4.Amer.pdf
http://storageconference.us/2014/Presentations/Panel4.Novak.pdf

http://storageconference.us/2014/index.html
http://storageconference.us/history.html

http://www.opencompute.org/wiki/Storage/Dev

http://www.snia.org/sites/default/files/Dunn-Feldman_SNIA_Tutorial_Shingled_Magnetic_Recording-r7_Final.pdf

=========



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