data migration by mirroring of volume - How is peformance affected ?

[hraju]

Our customer is considering to migrate data from old storage to new one with SFW. He is considering to do it during production time (so apps will have access to volume). They said, they used some other tool and performance (response time) was so degraded, they had to stop it.
I dont know what is the amount of data to be migrated, but I think that this would be the reason of why they consider migrating it during production.

Is it possible to use SFW to migrate data during production and how is performance degraded ?
AFAIK it is possible to create mirror during normal use of volume, but it is not recommended to use it a lot. In documentation I found:
"Adding mirrors to a volume involves a certain amount of time for mirror resynchronization. Take care not to perform actions on the volume until the command is complete."
There is also "Also, the generation of multiple mirrors does affect system resources"

Maybe "smartmove" or "fastresync" would help ?

any experiences with this ?

[Wally_Heim · Accepted solution]

Hi hraju,

Array migration using Mirrors can be done with data access still available to the storage.  There will be some degradation of application performance while the mirror is resyncing.  Symantec does not have any posted data numbers as to what performance degradation you will see.

SmartMove will help decrease initial synchonzation times of the mirror.  It does this by mirroring only the actual data on the drive using the NTFS filesystem.

I knwo that we do have many customers that do initial and rescyn mirror operations with live data. 

Thanks,
Wally


 

[Wally_Heim]

Hi hraju,

To clarify, SmartMove does not copy blank space on the volume because NTFS filesystem ignores this space until it writes something to it.

Thanks,
Wally