X-Git-Url: https://git.camperquake.de/gitweb.cgi?a=blobdiff_plain;f=man%2Fman5%2Fzpool-features.5;h=0ab179ef7c9002d8056789c663b88168bfef0f66;hb=87bdc45ccbf6f1d57a278c2026e60fc5f3af7598;hp=453e1ad2a47bf309d863b4b1dec574657d594805;hpb=9ae529ec5dbdc828ff8326beae58062971d74b2e;p=zfs.git diff --git a/man/man5/zpool-features.5 b/man/man5/zpool-features.5 index 453e1ad..0ab179e 100644 --- a/man/man5/zpool-features.5 +++ b/man/man5/zpool-features.5 @@ -20,8 +20,9 @@ zpool\-features \- ZFS pool feature descriptions .LP ZFS pool on\-disk format versions are specified via "features" which replace the old on\-disk format numbers (the last supported on\-disk format number is -28). To enable a feature on a pool use the \fBzpool\fR(1M) command to set -the \fBfeature@\fR\fIfeature_name\fR property to \fBenabled\fR. +28). To enable a feature on a pool use the \fBupgrade\fR subcommand of the +\fBzpool\fR(1M) command, or set the \fBfeature@\fR\fIfeature_name\fR property +to \fBenabled\fR. .sp .LP The pool format does not affect file system version compatibility or the ability @@ -168,5 +169,33 @@ through the \fBfreeing\fR property. This feature is only \fBactive\fR while \fBfreeing\fR is non\-zero. .RE + +.sp +.ne 2 +.na +\fB\fBempty_bpobj\fR\fR +.ad +.RS 4n +.TS +l l . +GUID com.delphix:empty_bpobj +READ\-ONLY COMPATIBLE yes +DEPENDENCIES none +.TE + +This feature increases the performance of creating and using a large +number of snapshots of a single filesystem or volume, and also reduces +the disk space required. + +When there are many snapshots, each snapshot uses many Block Pointer +Objects (bpobj's) to track blocks associated with that snapshot. +However, in common use cases, most of these bpobj's are empty. This +feature allows us to create each bpobj on-demand, thus eliminating the +empty bpobjs. + +This feature is \fBactive\fR while there are any filesystems, volumes, +or snapshots which were created after enabling this feature. +.RE + .SH "SEE ALSO" \fBzpool\fR(1M)