Advanced - EMC Symmetrix

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BCV Devices Requirement

Troubleshooting

FAQ

Best Practices

BCV Devices Requirement

Use the following matrix to calculate the number of target devices required for performing SnapProtect operations.

Agent Target Device Requirements (Business Continuance Volumes/ Shadow Image Volumes) NOTES
  full backup incremental backup differential backup  
DB2 [Number of devices where data resides] + [Number of devices where the online log resides] + [Number of devices where the 'LOCAL_DB_DIRECTORY' resides] + [Number of devices where the 'DBPATH' resides] N/A N/A  
Exchange Database [Number of devices where data resides] + [Number of devices where the log resides] [Number of devices where the log resides] [Number of devices where the log resides] For example, if your data resides on 2 devices, logs reside on 1 devices. Full backup will require 3(2+1) target devices, Incremental/Differential backup will require 1 target devices.
Microsoft SQL Server [Number of devices where data resides] + [Number of devices where the log resides]   [Number of devices where data resides] + [Number of devices where the log resides] For example, if your file system data resides on 3 devices you will require 3 target devices.

SQL log backup does not require any target device.
Microsoft Windows File System Number of devices on which the file system data resides Number of devices on which the file system data resides Number of devices on which the file system data resides  
NAS NDMP Number of devices on which the file system data resides      
Oracle [Number of devices where data resides] + [Number of devices where the log resides]   N/A  
Oracle – Data and logs residing on the same devices 2x[Number of devices where data and logs reside]   N/A For example, if your data and logs reside on 3 devices, you will require 6 target devices.
Applications running on JFS [Number of devices where application data resides] + [Number of devices where JFS logs reside] + [No. of devices on which logs reside]   N/A For example, if your application data resides on 2 devices, logs reside on 1 devices, data and logs share one device, and JFS logs reside on 1 device, you will require 6 (2+1+2+1) target devices
SAP for Oracle - Data and logs [Number of devices where data resides] + [Devise where the 'sapbackup' directory resides] + [Number of devices where the log resides] + [Device where the 'saparch' directory resides] + 2 x [Device where the 'dbs' directory resides] N/A N/A  
Unix File System [Number of devices where data resides] + [Number of devices where the log resides]      
Unix File System on JFS [Number of devices on which the file system data resides ] + [No. of devices on which file system logs reside]     For example, if your file system data resides on 2 devices and file system log resides on 1 device, you will require 3 target devices.
VMware Number of luns on which the datastore for the VM resides Number of luns on which the datastore for the VM resides N/A  
Microsoft Hyper-V Number of luns on which vhd and configuration files of VM reside Number of luns on which vhd and configuration files of VM reside N/A  

Troubleshooting

Snapshots are not being created

It is recommended that multiple SnapProtect backups using the same host must be run one after the other. Multiple SnapProtect backups running at the same time may cause the snapshot creation to fail due to the database lock.

Snapprotect backup failed

SnapProtect backup may fail when EMC Solutions Enabler software does not clean the SYMAPI database locks during abnormal termination of any process using SYMAPI. Additionally, this also causes the subsequent snapshot operations to hang indefinitely. As a workaround for this issue, reset the SYMAPI database locks using the EMC utilities or any other procedures provided by EMC.

Device Discovery Failed with Error 7143

If you run the symcfg discover command the Symmetrix CLI and completes with the following error in the MediaAgent log file, then the Symmetrix database was not successfully loaded:

CVSYMAPI::Discover() - SYMAPI - SymDiscover() failed with error (7143)

In the Symmetrix logs, you will also find the following error message:

Gatekeeper for the Symmetrix (Symm ArrayID) cannot be opened by the base daemon

As a workaround, ensure the Symmetrix gatekeeper is assigned from the array specified in the above error message. If the gatekeeper is assigned to the correct array ID, then set the MPIO policy as FAILOVER in the MPIO properties of the gatekeeper devices.

If you have multiple Symmetrix arrays, then a gatekeeper should be assigned for each array.

FAQ

How many LUNs can be assigned to a single port?

Ensure that there are not be more than 255 LUNs assigned to any single port, especially for Windows.

What are Device Groups?

Device Groups are a technique for grouping specific BCV and VDEV devices for clone or snapshot use. An example of Device Groups with a single BCV is shown on the right.

Device groups that are local to every client should have the following configuration:

  • The Device Group name must be the same for every client as during the array configuration you cannot specify more than one Device Group.
  • The source LUN and the BCV/VDEV devices must be part of the same Device Group.

 

Can I Use Multiple Device Groups?

When you configure an array using the CommCell Console, the Calypso software allows you to use one Device Group name. You can use multiple device groups by enabling the nDisableUseOfDG or nDisableDGChange registry key. Based on your environment, use the following configuration scenarios to use multiple device groups:

When using the registry keys, source and target devices will not be moved from the groups where they reside. Also, no new device groups will be created.

Configuration 1: Use the Device Group of the Source Device

Enable the nDisableDGChange registry key to ignore the device group you defined in the CommCell Console and to use the device group of the source device for SnapProtect operations. Before using this key, ensure the target device is present in the same device group as the source device.

This key is useful in the following scenarios:

  • You have device groups named differently on each client computer.
  • You have multiple device groups on the client computer. Each device group has source-target device pairs.

Configuration 2: Use Target Device from Different Device Group

Enable the nDisableUseOfDG registry key to use a target device from a different device group other than the source device group. The name of the devices group containing the target devices should be specified in Array Management.

This key is useful when you have all target devices in one device group and the source devices are scattered across multiple device groups.

How does the BCV device selection happen?

Calypso requires BCV and VDEV devices of the same block size to be created before performing SnapProtect operations. The BCV device selection occurs based on the following precedence:

How to Verify that a LUN is Mapped to a Host that Requires Protection?

To check if the LUN is already assigned to the server, run the following command on the server:

C:\> symdev -sid <symm_ID>

The physical device name may be displayed as "Not Visible" even if everything has been configured correctly (see image on the right). This may happen if you have multiple hosts that are doing the device management or if the SYMAPI DB has not been refreshed. You can try the following:

  • Check the Device Manager and Kernel Messages to ensure the disk is visible.
  • Refresh the SYMAPI DB using the following command:

    C:\> symcfg discover

If you still do not see the device properly, then you may need to configure/map the LUNs to the Host Adapter to make it visible to the Production Host.

How to Assign a new LUN to a Fiber Channel Director?

Before you proceed to assign a new LUN, ensure that proper hardware zoning has been completed for the Hot Bus Adaptors (HBAs) of the server to provide visibility to a Host Adapter.

The following example assumes that you are zoning the required HBA with Fiber Channel Director 10a / Port 1. Use the steps below to assign Symmetrix VOL 94 to LUN 0x31 – 49 (decimal) on FA-10a/Port 1:

1. Check if the device is unassigned or if it shows as "Not Visible":

C:\> symdev -sid 0546 list
2. Create a text file (e.g., test.txt) with the following content:

map dev 0094 to dir 10A:1 lun=31

  
3. Verify that the format of the text file has the correct syntax:

C:\> symconfigure -sid 0546 -f test.txt preview
4. Prepare Symmetrix for the configuration change. Check if there any locks (usually not for LUN mappings) to avoid making multiple configuration changes at the same time:

C:\> symconfigure -sid 0546 -f test.txt prepare
5. Commit the configuration changes:

C:\> symconfigure -sid 0546 -f test.txt commit

During the configuration change, a script runs on Symmetrix to load the new Configuration Files (IMPL) and allow device #0094 to be mapped to FA-10a / Port 1.
6. Confirm that device #0094 has been mapped to Host Adapter FA-10a / Port 1 as LUN 0x31 (49):

C:\> symdev -sid 000187880546 list
7. Make LUN mask device #0094 visible to HBA and assign it to WWN 21:00:00:E0:8B:07:A0:BC:

C:\> symmask -sid 0546 -wwn 210000E08B07A0BC -dir 10a -p 1 add devs 0094

Refresh the SYMAPI DB and verify the device is displayed properly as shown in the example.
8. Make the LUN available to the host by refreshing the device manager.

How does SnapProtect work with TimeFinder/Mirror?

Calypso always runs an Incremental Establish on BCV volumes. If there has been no prior TimeFinder operations on the BCV, then the Incremental automatically converts into a Full. See the following SYMAPI logs snippet which shows an Incremental Establish:

Assuming that device #006C is used as the Primary LUN to the production host, the following steps describe how to create a new TimeFinder/Mirror relationship with SnapProtect:

1. Create a new Device Group "test" to be used for SnapProtect.
2. Assign the BCV volumes to the "test" device group. C:\> symbcv –g test associate dev xxxx
3. Using the CommCell Console, create a new subclient for the LUN:
  • During the subclient configuration, ensure to select EMC TimeFinder BCV as the storage array.
  • Run a Full/Incremental backup job.
4. During the SnapProtect backup job, the "test" device group gets created, and during the snapshot creation, a synchronization is performed.

A BCV device cannot split until the synchronization completes. You can if the device is ready to split using the following command:

C:\> symmir -g test split
5. Once the synchronization completes, the "split" operation is automatically issued by the Calypso software.
6. During the cataloging phase, the host LUN mapping is adjusted for the BCV device #008D.
7. The BCV device is "un-masked". From the CommCell Console, you can see the snapshots created during the the SnapProtect job.

How does SnapProtect work with TimeFinder/Snap?

Similar to TimeFinder/Mirror, Calypso always require a new or recycled VDEV relationship to a single Production volume for each SnapProtect job. However, TimeFinder/Snap allows the LUN to be available to the production host by using the Copy-On-Write mechanism.

Assuming that device #0094 is used as the Primary LUN to the production host, the following steps describe how to create a new TimeFinder/Snap relationship with SnapProtect:

1. Create a new Device Group "test" to be used for SnapProtect.  
2. You must have a SAVE pool for VDEV volumes. You may use the DEFAULT_POOL.

In the example shown on the right, you can see that the DEFAULT_POOL has few devices and plenty of space. If you require further SAVE devices, you can create a text file (e.g., new_save_pool.txt) with the following content:

add dev 81:82 to pool DEFAULT_POOL, type=savedev, member_state=enable;

After creating the text file, run the following commands to add the extra devices to the SAVE:

C:\> symconfigure -sid 0546 -f c:\new_save_pool.txt -v -nop commit

 
3. Assign a VDEV volume to be used for TimeFinder/Snap.
4. Using the CommCell Console, create a new subclient for the LUN:
  • During the subclient configuration, ensure to select EMC TimeFinder Snap as the storage array.
  • Run a Full/Incremental backup job.
5. During the snapshot creation, Copy-On-Write operations are performed.

Once the snapshot is created, the snapshot will be mounted and cataloged, and the VDEV device will be "un-masked".

What are the SYMCLI Environment Variables I can use?

There are many environment variables that may aid in troubleshooting and potentially change some of the SnapProtect behavior. Please use these variables with caution. Consult with your EMC Storage Consultant if you are unsure of the impact these variable may cause.

Use the following command to retrieve the list of SYMCLI variables:

C:\> symcli -env

If I have RDF devices that are not paired, how can I use them for SnapProtect backup?

To use the RDF devices that are not paired, follow the steps given below:

  1. Create a RDF device group.
  2. Ensure that the source RDF device is a part of the device group created on the same machine.
  3. Add the Target VDEV/BCV to the same device group. Use the symdg add with -tgt option to add the target devices to the RDF device group.

How do I Back Up all of the devices that belong to a particular application?

Enable the bConsistentActivate registry key to create a consistent point-in-time image of the devices distributed across multiple sites. The key is used during activate operation for TimeFinder/Snap and TimeFinder/Clone and during Split operation for TimeFinder/Mirror. This is helpful while backing up all of the devices that belong to a particular application or backing up multiple devices distributed across multiple sites.

Can I use a different Save Device Pool for TimeFinder/Snap?

By default, TimeFinder Snap uses DEFAULT_POOL as the SAVE Device Pool for saving changed tracks from the source device.

Enable the sSaveDevicePool registry key to change the default SAVE Device Pool and use a different pool. The specified SAVE Device Pool Name is used with -svp option to TimeFinder/Snap create command.

Best Practices