# @pass-discard-other: whether discard requests for the data source
# should be issued on other occasions where a cluster gets freed
#
-# @discard-no-unref: when enabled, discards from the guest will not
-# cause cluster allocations to be relinquished. This prevents
-# qcow2 fragmentation that would be caused by such discards.
-# Besides potential performance degradation, such fragmentation
-# can lead to increased allocation of clusters past the end of the
-# image file, resulting in image files whose file length can grow
-# much larger than their guest disk size would suggest. If image
-# file length is of concern (e.g. when storing qcow2 images
-# directly on block devices), you should consider enabling this
-# option. (since 8.1)
+# @discard-no-unref: when enabled, data clusters will remain
+# preallocated when they are no longer used, e.g. because they are
+# discarded or converted to zero clusters. As usual, whether the
+# old data is discarded or kept on the protocol level (i.e. in the
+# image file) depends on the setting of the pass-discard-request
+# option. Keeping the clusters preallocated prevents qcow2
+# fragmentation that would otherwise be caused by freeing and
+# re-allocating them later. Besides potential performance
+# degradation, such fragmentation can lead to increased allocation
+# of clusters past the end of the image file, resulting in image
+# files whose file length can grow much larger than their guest disk
+# size would suggest. If image file length is of concern (e.g. when
+# storing qcow2 images directly on block devices), you should
+# consider enabling this option. (since 8.1)
#
# @overlap-check: which overlap checks to perform for writes to the
# image, defaults to 'cached' (since 2.2)
projects / mirror_qemu.git / blobdiff