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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: PH0PR04MB7416.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 1175948c-5de1-4eab-5704-08da398e237a X-MS-Exchange-CrossTenant-originalarrivaltime: 19 May 2022 11:53:06.9393 (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: gyiHzTWPXh4L9bU6SEl4L6E9ZwClukVkRFDz8kJWhqb7N2cTX3yHhRsddCN3GXrSljTBMhDIUsokeoXcyHx3qbl+TwXtStt6b+8nAOnJWi8= X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH0PR04MB7173 Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 19/05/2022 13:48, Qu Wenruo wrote:=0A= > =0A= > On 2022/5/19 19:44, Johannes Thumshirn wrote:=0A= >> On 19/05/2022 12:37, Qu Wenruo wrote:=0A= >>>> RAID1 on zoned only needs a stripe tree for data, not for meta-data/sy= stem,=0A= >>>> so it will work and we can bootstrap from it.=0A= >>>>=0A= >>> That sounds good.=0A= >>>=0A= >>> And in that case, we don't need to put stripe tree into system chunks a= t=0A= >>> all.=0A= >>>=0A= >>> So this method means, stripe tree is only useful for data.=0A= >>> Although it's less elegant, it's much saner.=0A= >> Yes and no. People still might want to use different metadata profiles t= han=0A= >> RAID1.=0A= > For RAID1 variants like RAID1C3/4, I guess we don't need stripe tree eith= er?=0A= > =0A= > What about DUP? If RAID1*/DUP/SINGLE all doesn't need stripe tree, I=0A= > believe that's already a pretty good profile set for most zoned device=0A= > users.=0A= > =0A= > Personally speaking, it would be much simpler to avoid bothering the=0A= > stripe tree for metadata.=0A= =0A= I totally agree, but once you get past say 10 drives you might want to have= =0A= different encoding schemes and also have a higher level of redundancy for y= our =0A= metadata than just 4 copies.=0A= =0A= The stripe tree will also hold any l2p information for erasure coded RAID = =0A= arrays once that's done.=0A= =0A= So this definitively should be considered.=0A=