continuous access logging to fata

[Lurkio]

Hi I am about to start creating some DR groups EVA6100 to EVA4400, FC disk to FC disk. Is it ok to use FATA disk for the Log at both ends?

[Uwe Zessin]

What type of logging do you intend to do?

For example in one of the planning quides it is written:
""IMPORTANT:
If you are using XCS 6.0 or later, create the DR group log using an online, fibre channel drive. Constant writes to the DR group log in enhanced asynchronous mode significantly shorten the expected lifetime of near on-line FATA drives.""


This year's EVA-4400 quickspecs have even started to disrecommend FATAl disk drives for CA replication targets when the source is on FC disks (when the FATAl disks were introduced this use was sold as a means to same great money):

""FATA drives are designed for lower duty cycle applications such as near on-line data replication for back-up. These drives should not be used as a replacement for EVA high performance, standard duty cycle, Fibre Channel drives. Doing so could shorten the life of the drive.
FATA drives are not recommended in Continuous Access applications as the remote storage location for local data residing on standard higher speed disk drives. Continuous Access tends to perform fairly high duty cycle random writes to the remote disk array. Matching remote FATA drives with local FC drives will impact the performance of your application, and will adversely impact the reliability of the FATA drives.""

[Lurkio]

Hi thanks for your Response Uwe.

When i create the DR group it is my understanding that by default CV creates a 100GB log file, this is used when there is a loss of connectivity between SANs. I am doing synchronous replication so i do not believe this log will be used unless there is a disruption to Comms. If i have misunderstood this process please let me know as i am fairly new CA

[Marcus Schack]

Lurkio, Uwe is right. HP no longer recommends the use of FATA drives for use with Continuous Access. It is best to only use FC drives. I know this, because I used to work for HP as the Storage Services Team lead for Canada. We had a lot of issues where customers used FATA drives for CA and ran into problems.