Am 11.06.2010 09:59, schrieb Jes Sorensen: > Could you please let us know whether this is still a problem and if it > isn't, lets close this bug.
This looks like a purely hypothetical thing - have you seen this happen in reality, and if so, with how many snapshots? This is reported against a very old version, so we have to assume 4k clusters. This means that a refcount block holds the refcounts for 4k / 2 = 2k clusters. Let's assume a refcount table of only one cluster, so we can describe (4k / 8) * 2k = 1M clusters with this, which makes up an image size of 4G. To hold a 20G virtual disk plus some metadata we'll therefore need something like 6 clusters = 24k. To make the refcount table consume just 1 MB, you'll therefore need at least 42 snapshots, each fully allocated on its own, consuming 1 TB for the image. I doubt that there are too many machines which can handle a 1 TB image file on disk, but not a 1 MB refcount table in RAM. Nowadays, of course, we're using 64k clusters by default. With a refcount table of 64k we describe 16 TB there, with a 1 MB refcount table it's 256 TB. Kevin
