onstat -d command: Print chunk information

Use the onstat -d command to show information about chunks in each storage space.

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Syntax:

>>-onstat-- -d--+--------+-------------------------------------><
                '-update-'   

The update option updates shared memory to obtain accurate counts of free pages.

Using onstat -d with sbspaces

For information about using onstat -d to determine the size of sbspaces, user-data areas, and metadata areas, see Monitor sbspaces.

Using onstat -d with blobspaces

If you run the onstat -d command on a server that has blobspace chunks, the database server displays the following message:
NOTE: For BLOB chunks, the number of free pages shown is out of date.
 Run ‘onstat -d update' for current stats.
To obtain the current statistics for blobspace chunks, run the onstat -d update command. The onstat utility updates shared memory with an accurate count of free pages for each blobspace chunk. The database server shows the following message:
Waiting for server to update BLOB chunk statistics ...

Example output

Figure 1. onstat -d command output
BM Informix Dynamic Server Version 14.10.F       -- On-Line -- Up 00:01:27 -- 133540 Kbytes

Dbspaces
address          number   flags      fchunk   nchunks  pgsize   flags    owner    name
4484a028         1        0x10020001 1        1        2048     N  BAE   informix rootdbs
45ed5b30         2        0x20001    2        1        2048     N  BA    informix space1
 2 active, 2047 maximum

Chunks
address          chunk/dbs     offset     size       free       bpages     flags pathname
4484a268         1      1      0          100000     65632                 PO-B-- /work3/AB/rootchunk
45f1f028         2      2      0          5000       4947                  PO-B-- /work3/AB/chunk5
 2 active, 32766 maximum

NOTE: The values in the "size" and "free" columns for DBspace chunks are
      displayed in terms of "pgsize" of the DBspace to which they belong.


Expanded chunk capacity mode: always

Output description for dbspaces

The first section of the output describes the storage spaces:
address
Is the address of the storage space in the shared-memory space table
number
Is the unique ID number of the storage space that is assigned at when it is created
flags
Uses hexadecimal values to describe each storage space. The individual flag values can be summed to show cumulative properties of the dbspace. The following table describes each hexadecimal value:
Table 1. Descriptions for each hexadecimal value
Flag Value Description
0x0001 Mirror is allowed and dbspace is unmirrored.
0x0002 Mirror is allowed and dbspace is mirrored.
0x0004 The dbspace contains disabled mirror chunks.
0x0008 Newly mirrored
0x0010 Blobspace
0x0200 Space is being recovered.
0x0400 Space is physically recovered.
0x0800 Logical log is being recovered.
0x2000 Temporary dbspace
0x4000 Blobspace is being backed up.
0x8000 Sbspace
0x10000 Physical or logical log changed.
0x20000 Dbspace or chunk tables changed.
0x040000 Blobspace contains large chunks.
0x080000 Chunk in this dbspace was renamed.
0x00100000 Temporary dbspace that is used by only by shared disk secondary server. It is one of the dbspaces listed in the SDS_TEMPDBS configuration parameter on the SD secondary server.
0x00200000 Temporary dbspace for the SD secondary server. Listed in the DBSPACETEMP configuration parameter on the shared disk secondary server.
0x00400000 The dbspace was externally backed up.
0x00800000 Dbspace is being defragmented.
0x01000000 Plogspace
0x10000000 The space is encrypted.
fchunk
The ID number of the first chunk
nchunks
The number of chunks in the storage space
pgsize
The size of the dbspace pages in bytes
flags
Uses the following letter codes to describe each storage space:
Position 1:
Flag Description
M Mirrored
N Not mirrored
Position 2:
Flag Description
X Newly mirrored
P Physically recovered, waiting for logical recovery
L Being logically recovered
R Being recovered
D Down
Position 3:
Flag Description
B Blobspace
P Plogspace
S Sbspace
T Temporary dbspace
U Temporary sbspace
W Temporary dbspace on primary server (This flag is shown on SD secondary servers only.)
Position 4:
Flag Description
B The dbspace can have large chunks that are greater than 2 GB.
Position 5:
Flag Description
A The dbspace is auto-expandable because the SP_AUTOEXPAND configuration parameter is enabled and the dbspace is configured with a create size or extend size that is not zero.
Position 6:
Flag Description
E The storage space is encrypted.
owner
The owner of the storage space
name
The name of the storage space

In the line immediately following the storage-space list, active refers to the current number of storage spaces in the database server instance, including the root dbspace and maximum refers to total allowable spaces for this database server instance.

Output description - Chunks

The second section of the onstat -d command output describes the chunks:
address
The address of the chunk
chk/dbs
The chunk number and the associated space number
offset
The offset into the file or raw device in base page size
size
The size of the chunk in terms of the page size of the dbspace to which it belongs.
free
The number of unallocated pages in the chunk in units of the page size of the associated dbspace. A value of 0 indicates that all the space in the chunk is allocated to tables, but does not indicate how much space is free inside the tables. For example, suppose you create a dbspace with one chunk of 200 MB and create one table with an extent size of 200 MB. The value of the free field is 0, indicating that the chunk has no free space, however, the new empty table has 200 MB of free space.

For a blobspace, a tilde indicates an approximate number of unallocated blobpages.

For an sbspace, indicates the number of unallocated pages of user data space and total user data space.

Note: The "onstat -d" output adds footnotes for each of the down chunks that are empty, and a special foot note for the first chunk of a down space that is empty.
Example Output for onstat -d with down space (due to first chunk out of 4), where 2 of the 4 chunks are empty and can be dropped:
Chunks
address          chunk/dbs     offset     size       free       bpages     flags pathname
44be2268         1      1      0          150000     83059                 PO-B-- /spaces/rootchunk
45c2b028         2      2      0          512        0                     PD-BE- /spaces/dbspace2_p_1
45c2c028         3      2      0          500        *                     PD-BE- /spaces/dbspace2_p_2
45c2d028         4      2      0          500        *                     PD-BE- /spaces/dbspace2_p_3
45c2e028         5      2      0          5000       0                     PD-BE- /spaces/dbspace2_p_4
5 active, 32766 maximum

NOTE: The values in the "size" and "free" columns for DBspace chunks are
      displayed in terms of "pgsize" of the DBspace to which they belong.

*  Down chunk is empty, and may be safely dropped.
Example Output for onstat -d when all chunks in down space are empty and can be dropped:
Chunks
address          chunk/dbs     offset     size       free       bpages     flags pathname
44be2268         1      1      0          150000     83059                 PO-B-- /spaces/rootchunk
45c2b028         2      2      0          512        **                    PD-BE- /spaces/dbspace2_p_1
45c2c028         3      2      0          500        *                     PD-BE- /spaces/dbspace2_p_2
45c2d028         4      2      0          500        *                     PD-BE- /spaces/dbspace2_p_3
45c2e028         5      2      0          5000       *                     PD-BE- /spaces/dbspace2_p_4
5 active, 32766 maximum

NOTE: The values in the "size" and "free" columns for DBspace chunks are
      displayed in terms of "pgsize" of the DBspace to which they belong.

*  Down chunk is empty, and may be safely dropped.
** Down space is empty, and may be safely dropped.
bpages
Is the size of the chunk in blobpages

Blobpages can be larger than disk pages; therefore, the bpages value can be less than the size value.

For an sbspace, is the size of the chunk in sbpages.

flags
Provides the chunk status information as follows:
Position 1:
Flag Description
P Primary
M Mirror
Position 2:
Flag Description
N Renamed and either Down or Inconsistent
O Online
D Down
X Newly mirrored
I Inconsistent
Position 3:
Flag Description
- Dbspace
B Blobspace
S Sbspace
Position 4:
Flag Description
B The dbspace can have large chunks that are greater than 2 GB.
Position 5:
Flag Description
E Identifies the chunk as extendable
- Identifies the chunk as not extendable
Position 6:
Flag Description
- The direct I/O or concurrent I/O option is not enabled for this cooked file chunk
C On AIX®, the concurrent I/O option is enabled for this cooked file chunk
D The direct I/O option is enabled for this cooked file chunk
pathname
The path name of the physical device

In the line immediately following the chunk list, active shows the number of active chunks (including the root chunk) and maximum shows the total number of chunks.

For information about page reads and page writes, run the onstat -D command.


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