<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto">ok<div><br></div><div>Ithanks</div><div><br></div><div><br></div><div><blockquote type="cite"><div dir="ltr"><span style="white-space: pre-wrap; display: block; width: 98vw;">pe_count(24) * extent_size(8192) = 196608 bytes usable space of the
> total dev_size(204800) metadata size? = dev_size(204800) - 196608 =
> 8192</span></div></blockquote></div><div><br><div dir="ltr">Sent from my iPhone</div><div dir="ltr"><br><blockquote type="cite">On 17 Sep 2020, at 17:22, Heinz Mauelshagen <heinzm@redhat.com> wrote:<br><br></blockquote></div><blockquote type="cite"><div dir="ltr">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
Tomas,<br>
<br>
the first PE starts at offset 2048 sectors of size 512 bytes by
default, i.e. the LVM MDA (metadata area)<br>
is ~1MiB big (because the MDA starts at offset 1 page into the
device). If you plan for large numbers of LVs or expect very
scattered allocations which both grow the metadata, you may want to
create a<br>
bigger MDA using vgcreate's option --metadatasize (also see
/etc/lvm/lvm.conf description on<br>
metadata/pvmetadatasize).<br>
<br>
On 9/16/20 5:50 PM, Tomas Dalebjörk wrote:<br>
<span style="white-space: pre-wrap; display: block; width: 98vw;">> hi
>
> I am trying to understand how big the lvm metadata is
>
> in the vgcfgbackup file, I can see extent_size = 8192 dev_size =
> 204800 pe_start = 2048 pe_count 24
>
> pe_count(24) * extent_size(8192) = 196608 bytes usable space of the
> total dev_size(204800) metadata size? = dev_size(204800) - 196608 =
> 8192
>
> but... pe_start is 2048? so what is pe_start here? cant be
> sectors(512)? bytes? well than ther be not aligned
>
> so where starts the actual data? and where ends the lvm metadata?
</span>
<p>At offset 2048 sectors (1MiB into the device) / MDA ends at
sector 2047.<br>
<br>
Mind that lvm2 metadata is text formatted (see
/etc/lvm/backup/$VGName for one)<br>
and thus varies in size (the MDA is used as a ring buffer for 2
copies of the MDA to<br>
support atomic updates). As pointed out above when refering to
'vgcreate --metadatasize',<br>
in more elaborate setups you may run out of MDA space.<br>
</p>
<p>Heinz<br>
</p>
<span style="white-space: pre-wrap; display: block; width: 98vw;">>
> regards Tomas Sent from my iPhone
>
>
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</div></blockquote></div></body></html>