Sizing the metadata area manually for a new chunk

Each chunk can contain metadata, but the sum total must accommodate enough room for all LO headers (average length 570 bytes each) and the chunk free list (which lists all the free extents in the chunk).

The following procedure assumes that you know the sbspace size and need to allocate more metadata space.

To size the metadata area manually for a new chunk:

  1. Use the onstat -d option to obtain the size of the current metadata area from the Metadata size field.
  2. Estimate the number of smart large objects that you expect to reside in the sbspace and their average size.
  3. Use the following formula to calculate the total size of the metadata area:
    Total metadata kilobytes = (LOcount*570)/1024 +
                               (numchunks*800) + 100 
    LOcount
    is the number of smart large objects that you expect to have in all sbspace chunks, including the new one.
    numchunks
    is the total number of chunks in the sbspace.
  4. To obtain the additional required area for metadata, subtract the current metadata size that you obtained in step 1 from the value that you obtained in step 3.
  5. When you add another chunk, specify in the -Ms option of the onspaces -a command the value that you obtained in step 4.

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