On 2/26/17 8:11 PM, Halsey Pian wrote: > Dear All, > > Recently, I try to read analyze the bitmap of XFS file system, it > seems that I cannot read the latest bitmap from hard disk involving > the XFS, and cannot read the accurate info even after a long time. > For example, i cannot get the relevant bitmap info after I add/delete > a big file to/from XFS file system. In general, attempting to read metadata from a mounted block device isn't going to be reliable. For one, changes may only be staged in the log, and not yet in their final disk location. > I tried several solution, and find it out that I must execute > xfs_freeze for the XFS partition in CentOS7, and it seems that > xfs_freeze doesn’t work for XFS version included in Redhat6.5, I must > umount/mount the xfs, then I can get the latest bitmap info related > to the latest data located in disk. > > What strategy does XFS use to cache/flush bitmap to hard disk? How > can I get the accurate bitmap info especially for Redhat6 series > Operating System? Could you please give help on it? The short answer is "you can't." Directly reading the block device while mounted isn't a supported use of the filesystem. What are you trying to do, here? Thanks, -Eric > Thanks in advance! ☺ > > > > > Halsey Pian > > > -- To unsubscribe from this list: send the line "unsubscribe > linux-xfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More > majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
