Why we fear when we hear about LVM metadata ?

It is very common that, people get scared as soon as they hear about LVM metadata.. I really dont know the reason, but I believe it is mainly because they think ‘metadata’ is not in human readable form ? , could be..

Any way, first of all let me tell you that, LVM metadata is an ASCII text…

It is, that simple to read:

See here an example of LVM metadata and its entries.

I have volume group called “MISC_VG_00001″ , the metadata of this volume group has below entries in it..

version = 1

description = "Created *before* executing 'lvcreate -L +100G -n MISC_LV MISC_VG'"

creation_host = "humbles-lap"   # Linux humbles-lap 2.6.34.7-61.fc13.x86_64 #1 SMP Tue Oct 19 04:06:30 UTC 2010 x86_64

creation_time = 1288624674      # Mon Nov  1 20:47:54 2010

MISC_VG {

        id = "5vLkK1-Dzc6-Vbwa-X0fP-AH9D-qEq4-rgAwcu"

        seqno = 1

        status = ["RESIZEABLE", "READ", "WRITE"]

        flags = []

        extent_size = 8192              # 4 Megabytes

        max_lv = 0

        max_pv = 0

        metadata_copies = 0

        physical_volumes {

                pv0 {

                        id = "btWJch-wdkf-UTpd-X74m-1Wke-sLF1-fI87qF"

                        device = "/dev/sda7"    # Hint only

                        status = ["ALLOCATABLE"]

                        flags = []

                        dev_size = 419435253    # 200.002 Gigabytes

                        pe_start = 384

                        pe_count = 51200        # 200 Gigabytes

                }

        }

}

Do you think I have to explain "metadata" entries from above ? I know answer is "NO" as it is self explanatory....
 
By the way , you can see LVM metadata copies under /etc/lvm/archieve and /etc/lvm/backup directories..
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