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Re: who creates 'dev/mapper/vgHDB-HDB9'?

Tom H wrote:
On Tue, May 3, 2011 at 12:41 PM, Hugo Vanwoerkom <hvw59601@care2.com> wrote:
I have installed lvm2 and created pv's, vg's and lv's. E.g.:

root@Debian:/home/hugo# lvdisplay
 --- Logical volume ---
 LV Name                /dev/vgHDB/HDB3
 VG Name                vgHDB
 LV UUID                SCHlBs-acvc-FLzz-TgwV-0IGX-aXBM-AdbPsB
 LV Write Access        read/write
 LV Status              available
 # open                 0
 LV Size                12.00 GiB
 Current LE             3072
 Segments               1
 Allocation             inherit
 Read ahead sectors     auto
 - currently set to     256
 Block device           254:1


and blkid says:

/dev/mapper/vgHDB-HDB3: LABEL="HD502HJ.03"
UUID="b12819b7-8f07-4bf6-af66-9bb9410536a1" TYPE="ext2"
/dev/mapper/vgHDB-HDB7: LABEL="HD502HJ.07"
UUID="c889aa6c-e0c3-4954-b8fe-b87d257c1cc6" TYPE="ext2"
/dev/mapper/vgHDB-HDB5: LABEL="HD502HJ.05"
UUID="18027b86-2b1f-4e24-ab5a-eb56ba0509c9" TYPE="ext2"
/dev/mapper/vgHDB-HDB6: LABEL="HD502HJ.06"
UUID="238dd5dc-012f-46e1-b680-84dbe9287d2b" TYPE="ext2"
/dev/mapper/vgHDB-HDBB: LABEL="HD502HJ.0B"
UUID="d7bc3d22-238a-47d4-86c8-6aa3384404e5" TYPE="ext2"

I have a question: who creates exactly those /dev/ entries?

The reason I ask is that sometimes with mondorescue they are not created and
I cnnot access the lv's.

I think that it's dmsetup - or a combination of dmsetup and udev.

Sure enough, from 'man dmsetup':

device_name [-u uuid] [--notable | --table <table> | table_file]

Creates a device with the given name. If table_file or <table> is supplied, the table is loaded and made live. Otherwise a table is read from standard input unless --notable is used. The optional uuid can be used in place of device_name in subsequent dmsetup commands. If successful a device will appear as /dev/device-mapper/<device-name>. See below for information on the table format.

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