if i have purchased 50GB of cloud storage and if 90% of it is utilized can we automatically buy additional 5 GB ( example)?
No, AWS doesn't allow such service with increment of 5 GB additionally.
Butr we can use EBS and EFS for such requirements where we might need storage increase.
if we take a EC2 service in one region automatically it is available across all Availability Zones in that region ... is this right? ( or should we select Availability zone)
while launching a EC2 we have to select a specific availability zone which doesn't make the instance or the service available in the region.
In order to do that we have to launch multiple instances in multiple availability zones to make it available within a region.
Cost varies from region to region for a specific service. So can we take different services from different regions to optimize cost?
yes cost varies from region to region. And a common strategy to optimize costs by strategically selecting different AWS services from different regions. This approach needs careful consideration of several factors, but when implemented correctly, it can lead to significant cost savings.
it is ok to have interruptions on batch processing. So i am going with Spot instance and if there is interruption can i restart this AUTOMATICALLY when next spot instance is available?
yes, we can restart the batch process where it got interrupted when the next spot instances is available.
i am sort of confused on this. Is interruption possible in on-demand instance like spot-instance?
no, on- demand cannot be interrupted like spot instances.