Posts Tagged ‘EMC’

Merging Fiber Channel Fabrics

December 3rd, 2008 No comments

You have two fabrics running off of two switches. You’d like to make them one fabric. How to do that? For the most part, it’s simply connecting the two switches via e_ports.

Before doing that, however, realize there’s several factors that can prevent them from merging

1. Incompatible operating parameters such as RA_TOV and ED_TOV
2. Duplicate domain IDs.
3. Incompatible zoning configurations
4. No principal switch (priority set to 255 on all switches)
5. No response from the switch (hello sent every 30 seconds)

To avoid the issues above:

1. Check IPs on all Service Processors and switches; deconflict as necessary.
2. Ensure that all switches have unique domain ids.
3. Ensure that operating parameters are the same.
4. Ensure there aren’t any zoning conflicts in the fabric (port zones, etc).

Once that’s done:

1. Physically link the switches
2. View the active zone set to ensure the merge happens.
3. Save the active zone set
4. Activate the new zone set.


December 3rd, 2008 No comments

Conceptually and operationally, SRDF is designed to work in a WAN/Internet/Cloud/SAN environment with multiple Symms involved, while Timefinder is local to a Symm, but performs the same functions.

The difference, SRDF can be performed without Geographic boundaries, while Timefinder is local. The following are various different forms of SRDF that can be used by a customer to perform SRDF operations. 

Synchronous mode

With Synchronous mode, the remote symm must have I/O in cache before the application receives the acknowledgement. Depending on distance where these Symmetrix machines are located, this may have a significant impact on performance. This form of SRDF is suggested to be implemented in a campus environment.

If you want to ensure that the data is replicated real time without dirty tracks from one symmetrix to the other, you might want to enable Domino effect. With Domino effect, your R1 devices will become not ready if the R2 devices cant be reached. 

Semi-synchronous mode

With Semi-synchronous mode, the I/O between the R1 and R2 devices are always out of sync. The application receives the acknowledgement from the first write I/O to the local cache. The second I/O isn’t acknowledged until the first is in the remote cache. This form of SRDF is faster than the previous mentioned Synchronous mode. 

Adaptive Copy-Write Pending

With Adaptive Copy-Write Pending, all the R2 volumes are copied over without the delay of acknowledgement from the application. With this mode, we can setup a skew parameter that will allow max number of dirty tracks. Once that number is reached, the system switches to a preconfigured mode like the semi-synchronous mode until the remote data is all synced. Once this is hit, SRDF is switched back to Adaptive Copy-Write Pending mode. 

SUN Host, EMC SAN, how to make it work?

December 2nd, 2008 No comments

EMC disks use luns vs scsi target numbers. SUN doesn’t normally use lun numbers so, to make the two talk together, you have to edit the /kernel/drv/sd.conf file as follows:

Normal, unedited file

name=”sd” class=”scsi”

target=0 lun=0;

name=”sd” class=”scsi”

target=1 lun=0;

Edited file

name=”sd” class=”scsi”

target=0 lun=0;

name=”sd” class=”scsi”

target=0 lun=1;

name=”sd” class=”scsi”

target=0 lun=2;

name=”sd” class=”scsi”

target=0 lun=8;

name=”sd” class=”scsi”

target=1 lun=0;

name=”sd” class=”scsi”

target=1 lun=1;

name=”sd” class=”scsi”

target=1 lun=2;

name=”sd” class=”scsi”

target=1 lun=8;

Add the luns for each of the EMC targets. Limit the targets to the EMC disks only, however, as the extra luns will dramatically increase the boot times on the system.

If you’re using more than 9 luns, make sure you use the hexadecimal notation for the lun numbers:


and ensure each lun line ends in a semicolon.

Split BCV’s

December 2nd, 2008 No comments

Based on the Timfinder BCV’s you split for backup or any other purposes, here is the info you need to figure how how to mount them or use them within your symm.

The issue revolves around the volume or disk group header information. Conceptually, this is the same for both Veritas Volume manager and HP’s Logical Volume Manager. Both volume managers store information about the volume/disk group on the disks that comprise the group. So, when you split off the BCVs, the information encoded is the exact same as the information on the standard devices. There won’t be a separate volume/disk group, LV/volume to mount because everything thinks its the same thing.

So, you have to figure a way around that. Fortunately, there’s a way for both HP’s Logical volume manager and Veritas’ Volume manager.

HP Logical volume manager – vgchgid

1. Split the BCV’s from the Symmetrix disk group. Example
1. /dev/dsk/c2t0d0
2. /dev/dsk/c2t1d0
3. /dev/dsk/c3t0d0
4. /dev/dsk/c3t1d0

2. Create an array with the appropriate disk names. Creating an array is optional.

set -A bcvs /dev/dsk/c2t0d0 /dev/dsk/c2t1d0 /dev/dsk/c3t0d0 /dev/dsk/c3t1d0

3. Create an vgexport map file for the volume group – particularly if you’re using nonstandard logical volume names.

vgexport -p -m /tmp/${vg}.map

4. Create the new volume group directory structure as needed:

mkdir /dev/vgbcv
mknod /dev/vgbcv/group c 64 0x0#0000

5. Change the volume group header information on all the BCV disks simultaneously:

/usr/sbin/vgchgid ${bcvs[*]}

6. Import the new volume group

vgimport -m /tmp/${vg}.map vgbcv ${bcvs[*]}

7. Mount the filesystems and do with them as you will.

Steps to import the clone disk (including EMC BCVs) using VxVM 5.0 :

1) before we split the BCV device from vm240dg (as in example below), “vxdisk list” shows the clone disk in an error udid_mismatch status

EMC0_1 auto:cdsdisk EMC0_1 vm240dg online
EMC0_27 auto – – error udid_mismatch

2) then issue the following command to split the BCV device

/usr/symcli/bin/symmir -g vm240dg split DEV001

3) after we split the BCV device DEV001 from vm240dg, we need to issue “vxdctl enable” or “vxdisk scandisks” to update the configuration in order to see the clone disk is in “online udid_mismatch” state issuing “vxdctl enable” ( or “vxdisk scandisks”), and “vxdisk list” gives the following display

EMC0_1 auto:cdsdisk EMC0_1 vm240dg online
EMC0_27 auto:cdsdisk – – online udid_mismatch

4) use the following comand to import the clone disk

vxdg -n newdg -o useclonedev=on -o updateid import vm240dg

5) issue “vxdisk list” to see the clone disk is imported

EMC0_1 auto:cdsdisk EMC0_1 vm240dg online
EMC0_27 auto:cdsdisk EMC0_1 newdg online clone_disk