Solution 217667 : VxVM - Unable to mirror a striped volume using 'vxassist' command

When attempting to grow a volume with a striped plex to a single disk with ample free space, vxassist complains that there is not enough space to perform the operation.

Here are the details of a generic case.

Start with a volume containing at least one striped plex:

  # vxprint -ht
 V  NAME      RVG      KSTATE   STATE    LENGTH    READPOL   PREFPLEX UTYPE
 PL NAME      VOLUME   KSTATE   STATE    LENGTH    LAYOUT    NCOL/WID MODE
 SD NAME      PLEX     DISK     DISKOFFS LENGTH    [COL/]OFF DEVICE   MODE

  v  vol01     -        ENABLED  ACTIVE   105906176 SELECT    -        fsgen
 pl vol01-01  vol01    ENABLED  ACTIVE   105907104 STRIPE    3/128    RW
 sd disk01-01 vol01-01 disk01   0        35302304  0/0       c4t3d0   ENA
 sd disk02-01 vol01-01 disk02   0        35302304  1/0       c4t7d0   ENA
 sd disk03-01 vol01-01 disk03   0        35302304  2/0       c4t23d0  ENA

and another disk with free space on which to mirror it:

  # vxdg -g ckdg free
 DISK         DEVICE       TAG          OFFSET    LENGTH    FLAGS
 disk09       c5t34d0s2    c5t34d0      0         143328960 -

However, when an attempt is made to mirror this volume using this disk, it fails with this error:

  # vxassist -g ckdg mirror vol01 alloc=disk09
 vxvm:vxassist: ERROR: Cannot allocate space to mirror 105906176 block volume

Resolution

The reason is that when mirroring a striped plex, the 'vxassist' command wants to create *another* striped plex as the mirror, by default. So, the command is failing not because there was not enough space to mirror it, but because there was not enough disks specified to create another striped plex.

To actually get vxassist to do what you want, that is, to mirror the striped plex to a new concat plex, you must use the 'layout=nostripe' option as well. Therefore, the command

  # vxassist -g ckdg mirror vol01 layout=nostripe alloc=disk09

will actually complete.