**6. Process of PCMGM**

146 Grid Computing – Technology and Applications, Widespread Coverage and New Horizons

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Because of the unstable of the cache node, the cache node can be joined or disjoined in dynamic. So the grid memory is changed in PCMGM. The dynamic adjusting mechanism for cache node must be discussed. We call the cache node which can't work for grid as the

**Definition.8. Computing density vector** is defined as *CDV*= (*cd1*, *cd2*… *cdp*), where *cdi* is the value of density allocation strategy of *CNi*. If *cdi* <*d,* we call *CNi* as the *low-density cache node*;

**Definition.9. Failure storage matrix** is defined as *FSM*= *(fqij)* (1≤*i*≤*m*, 1≤*j*≤*k*), where *fqij is DSEG* numbers of the *j* th segment of *CFi*, which *DSEG*s are stored in the *failure cache node*.

**Definition.10. effective storage matrix** is defined as *ESM*= *(eqij)* (1≤*i*≤*m*, 1≤*j*≤*k*), and

**Definition.11. Migration storage matrix** is defined as *MSM*= *(mqij)* (1≤*i*≤*m*, 1≤*j*≤*k*), where *mqij* is *DSEG* numbers of the *j* th segment of *CFi*, which *DSEG*s are stored in the *failure (or* 

1. Calculate the *DSEG*s which the current failure cache nodes include, and Construct the

2. Look for the low-density cache node by *CDV*, and get the free cache resources for *MSM*; Calculate the acceptable cache matrix *AMSM* by these resources, and *AMSM* will be migrated the new cache node; *MSM* – *AMSM* will be added into the failure storage

2. If the failure storage matrix is existed, we construct the migration storage matrix *MSM*

3. Look for the high-density cache node by *CDV*, and add their *DSEG*s information into

matrix *FSM* and *FSM* will be stored into the local disk which they are.

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*Mai*

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**5.5 Dynamic adjusting mechanism for cache node** 

If *cdi* >*d,* we call *CNi* as the *high-density cache node*;

The failure process description is as follows:

failure migration storage matrix *MSM*;

3. Revise the computing density vector *CDV*;

The new cache joining process description is as follows:

4. *MSM* will be migrated into the new cache nodes; 5. Revise the computing density vector *CDV*;

**5.5.2 Joining process of new cache node** 

1. Calculate the ability of *new cache nodes*;

*ESM*=*NCDM*-*FSM*.

**5.5.1 Failure process** 

by *FSM*;

*MSM*;

*Mai*

*failure cache node* and the new joined computer as the *new cache node*.

*overload ) cache node* , and the *DSEG*s of *MSM* will be migrated.

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The *DSEG*s in *CDM-NCDM* will be written into the local disk of cache node.

The PCMGM process is as follows:

