statvsd Command

Purpose

Displays virtual shared disk device driver statistics of a node.

Syntax

statvsd

Description

The statvsd command displays virtual shared disk statistics of a node. For example, on a busy server an increasing number of "requests queued waiting for a buddy buffer" is normal and does not necessarily imply a problem. Of more value is the "average buddy buffer wait_queue size" which is the number of requests queued for a buddy buffer when the statvsd command was issued. See the "Examples" section for the meaning of output lines.

Flags

None.

Parameters

None.

Security

You must be in the AIX® bin group to run this command.

Exit Status

0: Indicates the successful completion of the command.
nonzero: Indicates that an error occurred.

Restrictions

You must issue this command from a node that is online in the peer domain. To bring a peer domain online, use the startrpdomain command. To bring a particular node online in an existing peer domain, use the startrpnode command. For more information on creating and administering an RSCT peer domain, refer to the RSCT: Administration Guide.

Standard Output

Current RVSD subsystem run level.

Examples

The following examples display virtual shared disk device driver statistics.

The header line indicates the version and release of the code. For example:
```
VSD driver (vsdd): IP/SMP Version:4 Release:1
```
The level of virtual shared disk parallelism defaults to 9 and is the buf_cnt parameter on the uphysio call that the device driver makes in the kernel. For example:
```
9 vsd parallelism
```
The maximum IP message size in bytes. For example:
```
61440 vsd max IP message size
```
The number of requests that had to wait for a request block. For example:
```
61440 vsd max IP message size
```
The number of requests that had to wait for a pbuf (a buffer used for the actual physical I/O request submitted to the disk). For example:
```
0 requests queued waiting for a pbuf
```
The number of requests that had to wait for a buddy buffer. A buffer that is used on a server to temporarily store date for I/O operations originating at a client node. For example:
```
2689 requests queued waiting for a buddy buffer
```
The number of requests queued for a buddy buffer when the statvsd command was issued. For example:
```
0 average buddy buffer wait_queue size
```
The number of requests that a server has rejected, typically because of an out-of-range sequence number or an internal problem. For example:
```
4 rejected requests
```
The number of responses that a client has rejected. Typically because a response arrived after a retry was already sent to the server. For example:
```
0 rejected responses
```
The number of requests that were placed on the rework queue. For example:
```
0 requests rework
```
The number of read requests that were not on a 64 byte boundary. For example:
```
0 64 byte unaligned reads
```
The number of requests that got a DMA shortage. This condition would require the I/O operation to be executed in nonzero copy mode. For example:
```
0 DMA space shortage
```
The number of requests that have timed out. The current timeout period is approximately 15 minutes. For example:
```
0 timeouts
```
There are a fixed number of retries. The retries counters display the number of requests that have been retried for that particular "retry bucket." Numbers appearing further to the right represent requests that have required more retries. When a request exhausts its number of retries, it gets recorded as a timeout. For example:
```
retries: 0 0 0 0 0 0 0 0 0
 
          0 total retries
```

Sequence numbers are internally used by the device driver. These numbers are managed by the device driver and the Recoverable virtual shared disk subsystem. For example:

Non-zero Sequence Numbers
 
node#     expected     outgoing     outcase?     Incarnation:0
 11        125092         0            |
 
 11 Nodes Up with zero sequence numbers: 1 3 5 7 9 11 12 13 14 15 16

Location

/opt/rsct/vsd/bin/statvsd

Related Information

Commands: ctlvsd, vsdnode

Refer to RSCT: Managing Shared Disks for information on tuning virtual shared disk performance.