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Wong" , Johannes Thumshirn , Josef Bacik Subject: Re: [PATCH v10 05/41] btrfs: check and enable ZONED mode Thread-Topic: [PATCH v10 05/41] btrfs: check and enable ZONED mode Thread-Index: AQHWt1SX6TBkGrIRlEa+5WXQUx+StA== Date: Tue, 1 Dec 2020 11:03:35 +0000 Message-ID: References: <104218b8d66fec2e4121203b90e7673ddac19d6a.1605007036.git.naohiro.aota@wdc.com> <51c91510-6014-0dee-a456-b50648f48156@oracle.com> <20201127184439.GB6430@twin.jikos.cz> <4a784d16-b325-bf32-5ce5-0718c6bce252@oracle.com> <1dc43899-82de-564f-6e52-bd5b990f3887@cobb.uk.net> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: cobb.uk.net; dkim=none (message not signed) header.d=none;cobb.uk.net; dmarc=none action=none header.from=wdc.com; x-originating-ip: [129.253.182.59] x-ms-publictraffictype: Email x-ms-office365-filtering-ht: Tenant x-ms-office365-filtering-correlation-id: a3a89302-af2e-4806-b7e3-08d895e8bfaf x-ms-traffictypediagnostic: CH2PR04MB6726: x-ld-processed: b61c8803-16f3-4c35-9b17-6f65f441df86,ExtAddr x-ms-exchange-transport-forked: True x-microsoft-antispam-prvs: wdcipoutbound: EOP-TRUE x-ms-oob-tlc-oobclassifiers: OLM:10000; x-ms-exchange-senderadcheck: 1 x-microsoft-antispam: BCL:0; x-microsoft-antispam-message-info: 9SxkTPOGSs2BwyjL7pYD2KnO8k8uLXno75rDJspK1wLYx1r9gYxXNap+M/p7olCdGecgI42J2m8ChsJY7p07znigMGVwFC6zl9QL1WFIrcTLNhQOHHEPtlNs5rYQnYXvzzTgH8uWm84rDH5MqBHP2RmMnObzu+yCYRoYlrxXRa0LO14RlHnRg08bKdT3ZrB8EL3TlSdbqs1LhBjVXsTTP5Dqp2zrWbuExXx+eCYwHIJEVW782FcKKYvfeyuQ3LoaIsMOdfXrHb+LybpbOJGbONfCOWkiYdq+Eslc6Xf5bGZ4wJnMI93+RefXanOvKeR4L/uTHCOEx99Mh4VyCUMXYu8Nx5M/ePIxViLCm5+yfEk3heYlykS9pKpn21qo2HMt x-forefront-antispam-report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:CH2PR04MB6522.namprd04.prod.outlook.com;PTR:;CAT:NONE;SFS:(4636009)(366004)(376002)(39860400002)(136003)(396003)(346002)(9686003)(110136005)(7416002)(55016002)(33656002)(71200400001)(86362001)(478600001)(7696005)(2906002)(8676002)(5660300002)(26005)(83380400001)(52536014)(66446008)(921005)(186003)(91956017)(6506007)(76116006)(66476007)(8936002)(66556008)(316002)(53546011)(64756008)(66946007);DIR:OUT;SFP:1102; x-ms-exchange-antispam-messagedata: =?us-ascii?Q?tsCvbttu1GQikjt1Svlh/v7G9oFNA88fpTNtsySfwhit8Q1Py+PgcwQ/yIXj?= =?us-ascii?Q?1m+1hWoqmuY7Ro17qioDyeAU4a4wA2v7Mj6axUM3cHyvH4ukD8qv/txYxbia?= =?us-ascii?Q?8TTCEzSCUxTM1vRpHB+c8jwkK36uCJIzumJk0TUivDZ5dFJf5IH008FnA2XM?= =?us-ascii?Q?LVKPy/9jExn/2UTpFFX7vDi/kbwQOv7nwv7Zdz/WGZtBlmNA3XDY2M5fn0Hs?= =?us-ascii?Q?PizXv1sHxzOyGAOel+X/JB1WSBb93rn25xP+Rh97nDcE90+SC9ruUgjnPXJt?= =?us-ascii?Q?8qsy+lynV/WcviXrNQSudV/YT7bIU/7vl6aOGLa1D6WDZPOwYuDhjmEqoyLy?= =?us-ascii?Q?qwb3ICtuPAtpvwFeKfQRwWH16xmU5aoq0MXuqv0+eIWnnhqvvo+pvHvVBy+i?= =?us-ascii?Q?fw/s6WWHLkP4Pg+/th9KbLGGJuedwcww12vr2UGH6rjX8SSi2Z1I0AmD8KHy?= =?us-ascii?Q?Wi+QHVfwaS6lWzAN/Wy5t/Kv2dFBykJZlmb1RaN5sjYSwM75vZg2GlC9p5d6?= =?us-ascii?Q?DWMrdHEVEL4459CwcfEpiYZACR5XK8QRTl3dJbUOj//Cr84TJ/+JMhp7wF06?= =?us-ascii?Q?EPmI8I5/pLrCgbwM9dh70+FYfOSYhCNknQMze7ZCf723RqH1eWxioP/E6Lxn?= =?us-ascii?Q?xpP9oheJs7Xop6s+t4LDcBdCFYYSO1cxifJB1tsalCRAhGGsdQD3VrZ+ZPcB?= =?us-ascii?Q?wgVS9S5W39iUpcbL1+KMNPxTIeKugj9bj+3n49qSOglFFyNTwNnoAP7Hp5GU?= =?us-ascii?Q?/u5AqCjHiV94fETeVOHIgRLjUBeLtJzFg5/vKR3BL2S+aNblfRSheY0bRQzf?= =?us-ascii?Q?sABcpaxx8SwKiQQfHFuEyzfSDUYa5vI/T5nfV0D6BZg4MAaWHC12GsV7Gi5D?= =?us-ascii?Q?ZxPKYT6OQE/VacgTgEpebVkXoZUIUdmQ0jXHkyJYrznFs2duyqXGJ6oHUbdx?= =?us-ascii?Q?QqQoM2hq9t43e3n6qr8bZs3yvwjTnbHmP0qefhqO4bSvKUWI6YiO9AwFeUfz?= =?us-ascii?Q?8pRd?= Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: wdc.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: CH2PR04MB6522.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: a3a89302-af2e-4806-b7e3-08d895e8bfaf X-MS-Exchange-CrossTenant-originalarrivaltime: 01 Dec 2020 11:03:35.2984 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: b61c8803-16f3-4c35-9b17-6f65f441df86 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: BdCjDjRajl9RSKGb4y4OGd1iwtcN5O9UfRw+rCEjqpGf5ISN7j/r68kjJtpkdjWerqcdpYC2eSSFR9qGi2/KLw== X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH2PR04MB6726 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 2020/12/01 19:45, Graham Cobb wrote:=0A= > On 01/12/2020 02:29, Damien Le Moal wrote:=0A= >> Yes. These drives are fully backward compatible and accept random writes= =0A= >> anywhere. Performance however is potentially a different story as the dr= ive will=0A= >> eventually need to do internal garbage collection of some sort, exactly = like an=0A= >> SSD, but definitely not at SSD speeds :)=0A= >>=0A= >>> Are we ok to replace an HM device with a HA device? Or add a HA devic= e =0A= >>> to a btrfs on an HM device.=0A= >>=0A= >> We have a choice here: we can treat HA drives as regular devices or trea= t them=0A= >> as HM devices. Anything in between does not make sense. I am fine either= way,=0A= >> the main reason being that there are no HA drive on the market today tha= t I know=0A= >> of (this model did not have a lot of success due to the potentially very= =0A= >> unpredictable performance depending on the use case).=0A= > =0A= > So there will be no testing against HA drives? And no btrfs developers=0A= > will have one? And they have very different timing and possibly failure= =0A= > modes from "normal" disks when they do GC?=0A= > =0A= > I think there is no option but to disallow them. If HA drives start to=0A= > appear in significant numbers then that would be easy enough to change,= =0A= > after suitable testing.=0A= =0A= Works for me. Even simpler :)=0A= =0A= > =0A= >> Of note is that a host-aware drive will be reported by the block layer a= s=0A= >> BLK_ZONED_HA only as long as the drive does not have any partition. If i= t does,=0A= >> then the block layer will treat the drive as a regular disk.=0A= > =0A= > That is a bit of a shame. With that unfortunate decision in the block=0A= > layer, system managers need to realise that partitioning an HA disk=0A= > means they may be entering territory untested by their filesystem.=0A= =0A= Well, not really. HA drives, per specifications, are backward compatible. I= f=0A= they are partitioned, the block layer will force a regular drive mode use,= =0A= hiding their zoned interface, which is completely optional to use in the fi= rst=0A= place.=0A= =0A= If by "untested territory" you mean the possibility of hitting drive FW bug= s=0A= coming from the added complexity of internal GC, then I would argue that th= is is=0A= a common territory for any FS on any drive, especially SSDs: device FW bugs= do=0A= exist and show up from time to time, even on the simplest of drives.=0A= =0A= =0A= -- =0A= Damien Le Moal=0A= Western Digital Research=0A=