Thin LVM Metadata Size

[jai_123]

I am very new to Thin LVM.

Learned there are lot of chances for metadata corruption issue if exhaust the metadata space in Thin LVM. My logical volume looks as below:

[root@srv ~]# lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
lv1 volgroup1 twi-aotz-- 365.00g 1.61 1.23
lvol0 volgroup1 -wi-a----- 96.00m
vsv1001-08zrad volgroup1 Vwi-aotz-- 20.00g lv1 30.05

[root@srv ~]# lvscan
ACTIVE '/dev/volgroup1/lvol0' [96.00 MiB] inherit
ACTIVE '/dev/volgroup1/lv1' [365.00 GiB] inherit
ACTIVE '/dev/volgroup1/vsv1001-08zrad' [20.00 GiB] inherit

I have few questions:

1. In below 'lvs' command 1.23% is Meta%, do this means 1.23% of 365GB is used for META ?
2. How I can find the maximum metadata size for my logical volume.
3. Any performance impact by changing thin_pool_chunk_size or setting poolmetadatasize higher value.

Can someone please share your insight on this.

 

[jai_123]

I am answering to my question to document the knowledge in public.

You can use lvs -a to view details of metadata and pmspare

To extend metadata
lvextend -L+128M volgroup1/lv1_tmeta

You will see lvol0_pmspare (metadata spare) remains original size even after above command is successful.

"lvconvert --repair" process will re-create the spare metadata LV.

 

[skittle]

Checkout btrfs for some nice metadata goodness