EMC Symmetrix

What is the Fan-out ratio for an FA port on a Symmetrix V-Max

Fan-out ratio is a measure of the number of hosts that can access a storage port at any given time.This topology allows customers to map multiple host HBA ports onto a single FA port.The term fan-out is used to describe the server:storage ratio, where a graphic representation of a n:1 logical topology looks like a hand-held fan, with the wide end toward n. By convention fan-out refers to the number of server ports that share a single storage port. Fan-out consolidates a large number of server ports on a fewer number of storage ports. A fan-out rate is often referred to as just the n part of the ratio; For example, a 16:1 fan-out is also called a fan-out rate of 16, in this case 16 server ports are sharing a single storage port.

How to find which devices are causing high write pendings

Poor performance on disks due to high write pending count

This command will give the write pending tracks for all devices:

DEVICE	Tracks/sec	% Dev
17:32:07	WP Tracks	Prefchd	Destgd	WPmax
17:32:07 0081 (Not Visible )	6	0	0	0
0083 (Not Visible )	1	0	0	0
0088 (Not Visible )	12	0	0	0
0089 (Not Visible )	3	0	0	0
008A (Not Visible )	6	0	0	0
008E (Not Visible )	3	0	0	0
008F (Not Visible )	3	0	0	0
0083 (Not Visible )	1	0	0	0
0090 (Not Visible )	17	0	0	0
0091 (Not Visible )	0	0	0	0
0092 (Not Visible )	0	0	0	0
0093 (Not Visible )	0	0	0	0
0094 (Not Visible )	0	0	0	0
0095 (Not Visible )	0	0	0	0
0096 (Not Visible )	6	0	0	0

If you want to look at only a device group, use the following command:

symstat -sid 0000 -g groupname -type MEMIO -i 5 -c 5

How to recover SRDF Link Failure

1. symrdf -g dgname disable (Disables consistency protection for SRDF/A pairs in device group)
2. symrdf -g dgname set mode acp_disk (This will turn on the adaptive copy write pending mode for the device group)
3. symrdf -g dgname est (This initiates an establish for all the SRDF pairs in the device group)
4. symrdf -g dgname query (To query a device Group)
   Wait until the invalid track count is under 30,000 tracks
5. symrdf -g dgname set mode async (Change the Copy mode to Asynchronous)
6. symrdf -g dgname enable (Enables consistency protection for SRDF/A pairs in device group)

SYMCLI Command Line Examples

To check symcli version - symcli To check Microcode version - symcfg list To check the Build version of microcode - symcfg list -v To check the FA's on the symmetrix - symcfg -sid 1234 -fa all list To check the FA connectivity status - symcfg -sid 1234 -fa all list -port Note :(X)…

How to add new dynamic pairs to an existing device group in SRDF

In this example I will show you how to add new dynamic pairs to an existing device group in srdf. VMAX R1 Frame : 1344VMAX R2 Frame : 1719Device Group : njserver_dg Device Group (DG) Name : njserver_dg DG's Type : RDF1DG's Symmetrix ID : 000192601344 (Microcode Version: 5876)Remote Symmetrix…