Difference between symmir and symclone

Question

I have been using symmir and unprotected BCVs to get copies of prod database for testing and backups. We are migrating our data to a DMX4 and will have protected BCVs (RAID-5). EMC has mentioned the symclone command to get the copies. Should the symclone command be used instead of symmir because the BCV devices are protected or is the symclone command a replacement for symmir?

xe2sdc · Accepted Answer

Hi Danne (I hope it's your name)

symmir is the CLI you use to manage the "good old" TimeFinder/Mirror ... With TF/Mirror you use very special devices (marked as BCV) to create copies of your STD devices. Since it looks like you still have BCV devices in your DMX4, your good old symmir command will work flawless right as before. The only "small" change is behind the curtains .. The symmir command will "trigger" TF/Clone operations when you have RAID-protected BCV devices.

TF/Clone is another member of our TF family that gives you more flexibility, a few different options and a completly different behaviour if you are used to TF/Mirror.

I guess you can stick with symmir command if you have Raid5-BCV devices .. symmir will do the trick for you

Danne-Murphy · Answer

Thanks for the information. I took a quick look at the syntax and it appears to be very similar to the open/replicator syntax we are using to migrate to the DMX4. I never had any problems with symmir, but I guess I have to move forward. I will look at the new options and may find a reason to utilize it.

xe2sdc · Answer

If your have RAID protected BCVs you don't need to move "forward" .. Clone is neither forward or backward .. they are cheek to cheek ;-)

As you noticed OR have almost the same syntax .. first you "create" sessions and you "activate" them when you reached consistency on SRC devices .. In TF/Mirror terms you first establish the devices and later you split them when SRC is consistent ;-)

The main difference between TF/Mirror and TF/Clone is that TF/Clone by default copies only changed tracks and that the copy process begins AFTER activation while with TF/Mirror you always have a full copy of your data on BCV devices (even after an incremental establish) and you copy data BEFORE splitting the BCV devices.
The good news is that Clones have further options allowing you to have a full copy of your devices and even to begin copying data right after creation (just like OR does). That's why clones can EMULATE TF/Mirror ;-)

Jayan3 · Answer

One notable difference is that

symmir need to have devices with BCV attribute to create a mirror copy.

symclone can be done on any standard device (no need to have a device with BCV attribute).

thanks
Jayan

Host Systems

Difference between symmir and symclone