ONTAP Hardware

Replacing disks by larger ones (II)



I read the KB article under https://now.netapp.com/Knowledgebase/solutionarea.asp?id=kb21090 because I have the task to replace some smaller disks (320GB SATA) by bigger ones (1TB SATA).

In the article is written:

"However, if either parity disk was of the smaller drive size, any larger drive added to the RAID group would be downsized" - so I thought the trick is, to replace the parity disks first and then everything is fine.

But actually my sysconfig-r gives the following output:

RAID Disk Device HA  SHELF BAY CHAN Pool Type  RPM  Used (MB/blks)    Phys (MB/blks)
---------------------------- ---- ---- ---- ----- --------------    --------------
dparity      0c.61   0c    3        13    FC:B     -    ATA   7200  847555/1735794176 847827/1736350304
parity        0a.48  0a    3          0    FC:A     -    ATA   7200  274400/561971200  847827/1736350304
data          0a.54  0a    3          6    FC:A     -    ATA   7200  274400/561971200  847827/1736350304
data         0c.19   0c    1         3     FC:B     -   ATA   7200  274400/561971200  274540/562258784 (replacing, copy in progress)
-> copy    0a.56   0a    3         8     FC:A     -   ATA   7200  274400/561971200  847827/1736350304 (copy 99% completed)
data        0a.20   0a    1         4     FC:A     -    ATA   7200  274400/561971200  274540/562258784
data        0c.21   0c    1         5     FC:B     -    ATA   7200  274400/561971200  274540/562258784

As one can see, this seemed to work for the dparity disk, showing the full right-sized of 827GB as used, but the parity was downsized to 268GB, and because of that it is clear to me, that all the following disk are also downsized.

Well, know I know the threads in this community like




stating, that it is not possible to replace disks in this way.

But the question then remains: why was the dparity disk not downsized to 268GB?!

And isn't there really no way to get the parity disk now replaced and sized to 827GB - because then I still believe all the other 1TB-disks would not be downsized....




Replacing the parity disks won't make the data disks stay at the larger capacity...at least for a replacement.  They may stay if you just add disks to the end of the RG, but if you do any kind of replacement of a larger drive for a smaller drive, I would expect that disk to be downsized regardless of the size of the parity disks.

If you really want to replace smaller drives with larger ones, the right way to do it is to copy the data over, then do a cut-over.