WP issues are pretty simple.  Either slow the writes into the system, or increase the speed of the destage.  Adding cache generally does not help much.

You can limit the writes into the system by reducing the paths into the system, or the queue depth.

You can increase the destage rate by increasing the number of disks or DAs and/or the raid protection.

That's the main reason I refuse to let my DBA team use the vMax as a backup device. Another solution, and in my opinion a better solution, is to purchase a small disk array or a tray of disk for this purpose.

On a side note, one would think a storage company would add DBA and vMax to the site dictionary.

With regard to your search, how did you perform it and what browser are you using? You should have been able to do a search on DBA and VMAX. However, there have been issues with Internet Explorer. Using Mozilla Firefox may solve the problem.

They're not in the site spell checker.

Can you explain littile about  below point ?

"You can increase the destage rate by increasing the number of disks or DAs and/or the raid protection"

Write cache is simply a buffer between the host and the disks.  If the disks can't keep up with the host write rate, the buffer will fill and the host will be slowed to the rate of the destage on the disks.

If the disks can destage faster than the host is writing, then the host will always be able to write to cache with no delay because the buffer is full.   Fewer drives can destage slower than more drives. RAID1 can desage faster than RAID5 which can desage faster than RAID6.  Put enough drives behind a DA CPU, and the DA CPU can be the limiting factor for the destage rate, so in that case, more DAs can increase the destage rate.

Need more explanation?

Currently we are using RAID 5 drive for our backup drive(to which we will dump the SQL backup).So If we configure it with a RAID 1 we can increase the destage rate right which inturn reduce WP. right ?

With thick you need to make sure your meta is the same width as the disks you are writing to.  For example if you had 16 total drives with 3+1 protection, your meta volume should have 4 members so that you have one member on each raid group.  If it wraps around, it will increase the seek time.  If it doesn't touch all the drives, you won't get the advantage of all the disks.

You can also consider DCP (Dynamic Cache Partitioning) to fence these writes so they don't impact the the whole system.

This is a Thick one and I am using a meta volume.

I am working with my SQL team to re arrange the backup timings to reduce the writes to storage in a given time