New feature which was introduced with SQL Server 2016 is Stretch Database which migrates our historical data transparently and securely to the Microsoft Azure SQL cloud. Stretch Database provides some benefits to the users, but also has its own limitations which make it less likely to be used as of now, unless Microsoft comes up with significant improvements. Stretch Database in a SQL Server instance requires at least one table. It then silently begins to migrate the historical data to Azure SQL Database. If we are storing historical data in a separate table, then we can migrate the entire table. If our table contains both historical and current data, then we can specify a filter predicate to select the rows which need to be moved to Azure SQL database. Also, importantly, Stretch Database ensures that no data is lost if a failure occurs during migration. There is also retry logic to handle intermittent connection issues that may occur during migration.
Stretch Database lets us choose retention times of our choice even for large amounts of data without breaking the bank. Depending on our performance requirements, we can choose a performance level, and then scale up or down as needed. Stretch Database charges for Compute and Storage are charged separately, so we choose to only pay for what we use. Compute usage is represented as Database Stretch Unit (DSU) and customers can scale up and down the level of performance/DSUs that we need at any time. We have options for pricing based on different locations based on the currency. If we consider USD, below are the sample pricing options for usage of computing resources,
PERFORMANCE LEVEL(DSU) PRICE
100 $1.25/hr (~$930/mo)
200 $2.50/hr (~$1,860/mo)
300 $3.75/hr (~$2,790/mo)
400 $5/hr (~$3,720/mo)
500 $6.25/hr (~$4,650/mo)
600 $7.50/hr (~$5,580/mo)
1000 $12.50/hr (~$9,300/mo)
1200 $15/hr (~$11,160/mo)
1500 $18.75/hr (~$13,950/mo)
2000 $25/hr (~$18,600/mo)
Another pricing part which we need to pay separately for is storage. Storage rates are based on standard RA-GRS Page Blob rates. Storage transactions are not billed; customers only pay for data stored, not storage transactions.
Here Data Transfers refer to data moving in and out of Azure data centers other than those explicitly covered by the Content Delivery Network or ExpressRoute pricing.
LRS GRS RA-GRS
COOL HOT COOL HOT COOL HOT
First 100 TB / Month $0.01 $0.024 $0.02 $0.048 $0.025 $0.061
Next 900 TB / Month $0.01 $0.0232 $0.02 $0.0463 $0.025 $0.0589
Next 4,000 TB / Month $0.01 $0.0223 $0.02 $0.0446 $0.025 $0.0567
LOCALLY REDUNDANT STORAGE (LRS) – Makes multiple synchronous copies of your data within a single datacenter.
ZONE REDUNDANT STORAGE (ZRS) – Stores three copies of data across multiple datacenters within or across regions. For block blobs only.
GEOGRAPHICALLY REDUNDANT STORAGE (GRS) – Same as LRS, plus multiple asynchronous copies to a second datacenter hundreds of miles away.
READ-ACCESS GEOGRAPHICALLY REDUNDANT STORAGE (RA-GRS) – Same as GRS, plus read access to the secondary datacenter
OUTBOUND DATA TRANSFERS ZONE 1* ZONE 2* ZONE 3*
First 5 GB/Month Free Free Free
5 GB – 10.0 TB $0.087 per GB $0.138 per GB $0.181 per GB
Next 40 TB
(10-50 TB)/month $0.083 per GB $0.135 per GB $0.175 per GB
Next 100 TB
(50-150 TB)/month $0.07 per GB $0.13 per GB $0.17 per GB
Next 350 TB
(150-500 TB)/month $0.05 per GB $0.12 per GB $0.16 per GB
Outbound data transfers are charged at regular data transfer rates. A sub-region is the lowest level geo-location that you may select to deploy your applications and associated data. For data transfers (except CDN), the following regions correspond to Zone 1, Zone 2 and Zone 3.
Zone 1: US West, US East, US North Central, US South Central, US East 2, US Central, Europe West, Europe North
Zone 2: Asia Pacific East, Asia Pacific Southeast, Japan East, Japan West, Australia East, Australia Southeast
Zone 3: Brazil South.
There can be discounts to these prices based on region, number of servers, amount of compute and storage brought.
Hope this was helpful.
This is applicable for below versions of SQL Server
SQL Server 2016
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