PVG완전미러링

[watermelonyu]

PVG완전미러링이라는게 무엇인가요? 서비스가드의 메뉴얼에 나와있는데 아무리 읽어도 이해가 안됩니다. 그림이라도 있으면 알텐데 어렵네요.



설명부탁드려도 될까요?

[김병수]

보통의 경우 mirror는 logical volume를 사용하지만....



PVG는 말그대로 physical volume group mirror입니다.



아래에 사용예가 있습니다.



참고하시기 바랍니다.



Systems with mirrored logical volumes often use multiple SCSI controllers to be able to work on in case of hardware failure. To secure that the mirrored extents of a logical volume can always be established on a disk not connected to the same card, PVGs - Physical Volume Groups can be created:

# vgcreate -g vgXY /dev/dsk/cCtTdA /dev/dsk/cCtTdB ...



All stated physical volumes are part of the new PVG.



Further PVGs for an existing volume group can be created or extended by using the vgextend command.



The information of the Physical Volume Group is stored in the ASCII file /etc/lvmpvg. This file can also be created or extended manually, instead of using the vgcreate and vgextend commands. lvmpvg stores the volume-group information for all of the physical volume groups in the system. The information is stored in a hierarchical format. First, it starts with a volume group under which multiple physical volume groups can exist. Under each physical volume group, a list of physical volumes can be specified. There must be at least one physical volume group in each volume group that appears in this file. The physical-volume-group name must be unique within the corresponding volume group, although it is permissible to use a common physical volume group name across different volume groups. There can be as many volume groups in this file as there are in the system.



At following example of /etc/lvmpvg, four hard disks are connected to two SCSI controllers.



# cat /etc/lvmpvg



VG /dev/vg01

PVG scsi0

/dev/dsk/c0t6d0

/dev/dsk/c0t5d0

PVG scsi1

/dev/dsk/c1t2d0

/dev/dsk/c1t1d0



The volume group shows up as follows:



# vgdisplay -v /dev/vg01



...

--- Physical volume groups ---

PVG Name scsi0

PV Name /dev/dsk/c0t6d0

PV Name /dev/dsk/c0t5d0



PVG Name scsi1

PV Name /dev/dsk/c1t1d

PV Name /dev/dsk/c1t2d0