From: Goffredo Baroncelli <kreij...@inwind.it> --- man/btrfs.8.in | 94 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 94 insertions(+)
diff --git a/man/btrfs.8.in b/man/btrfs.8.in index 4b0a9f9..3215216 100644 --- a/man/btrfs.8.in +++ b/man/btrfs.8.in @@ -27,6 +27,8 @@ btrfs \- control a btrfs filesystem .PP \fBbtrfs\fP \fBfilesystem label\fP\fI <dev> [newlabel]\fP .PP +\fBbtrfs\fP \fBfilesystem disk-usage\fP\fI [-s][-d][-k] \fIpath [path..]\fR\fP +.PP \fBbtrfs\fP \fBsubvolume find-new\fP\fI <subvolume> <last_gen>\fP .PP \fBbtrfs\fP \fBfilesystem balance\fP\fI <path> \fP @@ -214,6 +216,98 @@ NOTE: Currently there are the following limitations: - the filesystem should not have more than one device. .TP +\fBfilesystem disk-usage\fP [-s][-d][-k] \fIpath [path..]\fR + +Show space usage information for a mount point. + +\fIOptions\fP + +\fB-k\fP Set KB (1024 bytes) as unit + +\fB-s\fP Don't show the summary section + +\fB-d\fP Don't show the detail section + +\fIUsage information\fP + +.\" +.\" this section is extract from +.\" http://en.wikipedia.org/wiki/Btrfs#Chunk_and_device_trees +The disk(s) of a btrfs filesystem are divided into chunks of 256 MB or more. +Chunks may be mirrored or striped across multiple devices, depending by +the allocation policy. +The mirroring/striping arrangement is transparent to the rest of the +file system, which simply sees the single, logical address space that +chunks are mapped into. +Chunks are allocated on demand. In the default allocation policy +the data chunks are not duplicated and the metadata chunks +are duplicated. This default can be changed during the filesystem +creation, and in general the chunks allocation policy may change +during the filesystem life. + +A chunk DUPlicated or with a RAID1/RAID10 level +requires a space two time greater than the logical one. Different RAID levels +have a different ratio disk-usage / logical space offered. + +Because some files (the small ones) are stored in the +metadata chunks the computation of the \fIfree space\fP and \fIused space\fP +is complex: depending by the file size different allocation policies are used. + +The command \fBbtrfs filesystem disk-usage\fP is used to query the status +of the chunks, how many space on the disk(s) are used by the chunks, +how many space are available in the chunks, and an estimation of the free +space of the filesystem. +The output of the command \fBbtrfs filesystem disk-usage\fP shows: + +.RS +.IP Disk\ size +the total size of the disks which compose the filesystem. + +.IP Disk\ allocated +the size of the area of the disks used by the chunks. + +.IP Disk\ unallocated +the size of the area of the disks which is free (i.e. +the differences of the values above). + +.IP Logical\ size +the available logical space of chunk. + +.IP Used +the portion of the logical space used by the file and metadata. + +.IP Free\ (estimated) +the estimated free space available. The evaluation +cannot be rigorous because it depends by the allocation policy (DUP,Single, +RAID1...) of the metadata and data chunks. If every chunks is stored as +"Single" the sum of the \fBfree (estimated)\fP space and the \fBused\fP +space is equal to the \fBdisk size\fP. +Otherwise if all the chunk are mirrored (raid1 or raid10) or duplicated +the sum of the \fBfree (estimated)\fP space and the \fBused\fP space is +half of the \fBdisk size\fP. Normally the \fBfree (estimated)\fP is between +these two limits. + +.IP Data\ to\ disk\ ratio +the ratio betwen the \fBlogical size\fP and the \fBdisk allocated\fP. + +.IP Mode +the kind of allocation policy used by the chunk (e.g. DUPlicated, +RAID1, RAID10, Single....) + +.RE +.RS +\fINOTE\fP + +When a chunk is allocated, its disk-area is used and its allocation +policy is fixed. +A rebalance operation could rearrange the chunks, moving data in the chunks +and resizing the allocated chunks. This causes the change of all the values +discussed above, with the exception of the \fBused\fP and +\fBdisk size\fP values. + +.RE +.TP + \fBfilesystem show\fR [--all-devices|<uuid>|<label>]\fR Show the btrfs filesystem with some additional info. If no \fIUUID\fP or \fIlabel\fP is passed, \fBbtrfs\fR show info of all the btrfs filesystem. -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html