On Mon, Aug 29, 2022 at 10:26:20AM +0800, Wang Yugui wrote: > Hi, > > I saw some info about hybird xfs wih ssd/hdd by realtime subvol. > > Hybrid XFS—Using SSDs to Supercharge HDDs at Facebook > https://www.usenix.org/conference/srecon19asia/presentation/shamasunder > > There are some questions about how to control the data to save into > normal vol or realtime subvol firstly. > > 1, man xfsctl > here is XFS_XFLAG_REALTIME in man xfsctl of xfsprogs 5.0 , > but there is no XFS_XFLAG_REALTIME in xfsprogs 5.14/5.19. > xfsctl(XFS_XFLAG_REALTIME) will be removed in the further? It's been a while since XFS uses FS_XFLAG features directly, so, what you're specifically looking for is FS_XFLAG_REALTIME. xfsprogs today only has a preprocessor define: #define XFS_XFLAG_REALTIME FS_XFLAG_REALTIME FS_XFLAG_REALTIME is part of the xfs realtime, unlikely it's going away without the realtime filesystems going first, so, unlikely it's gonna happen. > > 2, Is there some tool to do xfsctl(XFS_XFLAG_REALTIME)? You can use xfs_io's chattr command to add/remote the REALTIME attribute of a file. > > 3, we build a xfs filesystem with 1G device and 1G rtdev device. and > then we can save 2G data into this xfs filesystem. > > Is there any tool/kernel option/kernel patch to control the data to save > into normal vol or realtime subvol firstly? I didn't watch the talk you mentioned above, but when use an rt device, you don't use the 'normal' one then the rt later, or vice-versa, the rt-device is used to store data blocks for those files marked with the xattr above. For those files you want to store in the realtime device, you should add the above xattr to them. Cheers. -- Carlos Maiolino
