NetApp Performance Consitency Point Pacing cp_batch_override

During a consistency point, the data is written from memory to disk. This action requires calculating the RAID (XOR processing). The XOR processing is CPU intensive and is carefully calibrated by ONTAP. This is called CP pacing.


CP pacing controls the XOR batch processing size, which is the main CPU factor with regards to RAID processing for CP.

If the CP pacing  increases the batch size then XOR  threads consume more CPU and process data faster. Thus a tetris is handed off to storage layer quicker.

CP pacing also looks at the outstanding blocks required to be written for the current CP versus the resource fill for the next CP to adjust the batch size. For ex: When blocks written is less than the next CP fill , the batch size is increased.

The CP pacing batch size varies from 1 to 18.

Thus, cp_batch_override 18 means run XOR as fast as possible, which should decrease the P2_FLUSH time, assuming there is no actual storage issue.

VMware RDM Correlating VML ID with naa ID

Where:

A - represents the external ID name space.

B - represents uuid type for the device:

0x0 - For mpx.vmhbax:Cx:Tx:Lx format

0x1 - For serial number format

0x2 - For naa format

0x3 - For SYMM format

C - represents the device type:

0x00 - DISK

0x01 - TAPE

0x02 - PRINTER

0x03 - PROCESSOR /* HP scanners use this */

0x04 - WORM /* Treated as ROM by our system */

0x05 - ROM 0x05

0x06 - SCANNER

0x07 - MOD /* Magneto-optical disk - * - treated as TYPE_DISK */

0x08 - MEDIUM_CHANGER

0x09 - COMM /* Communications device */

0x0c - RAID

0x0d - ENCLOSURE 0x0d /* Enclosure Services Device */

0x0e - RBC 0x0e

0x7f - NO_LUN

D - represents LUN number (32 bits in normal device from SAN)

E - is reserved for future use

F - represents the LUN identifier (32 digit naa number in hexadecimal format)

G - A unique hash of other data about the LUN (In versions prior to 5.5 includes the LUN number)

SMB shares created by Default in NetApp

Here is the list of shares created by NetApp when SMB is enabled.

For 7 mode :
        C$  and it points to /.
        ETC$ and it points to /etc.
        HOME and it points to /vol/vol0/home

For ClusteredONTAP:
        C$ maps to /.
        ipc$ maps to /.
        admin$ maps to /.