Three copies or six?

Copies in the primary region

Azure Storage always stores multiple copies of your data so a failed drive or server doesn't lose it. Two choices keep all copies in the primary region:

• Locally redundant storage (LRS): three copies in one datacenter. Cheapest; survives a failed disk or rack, not a disaster that takes out the datacenter. At least 11 nines (99.999999999%) durability a year
• Zone-redundant storage (ZRS): three copies spread across three availability zones in the region. Data stays available even if a whole zone goes down. At least 12 nines

Copies in a second region

The geo options add three more copies in a secondary region hundreds of miles away, usually the primary region's pair: six copies in total. Data is copied to the secondary region asynchronously.

• Geo-redundant storage (GRS): LRS in the primary region plus LRS in the secondary region
• Geo-zone-redundant storage (GZRS): ZRS in the primary region plus LRS in the secondary region. The most protection: survives a zone outage and a regional disaster

Exam tip GRS and GZRS are designed for at least 16 nines of durability. Their secondary copies can't be read until a failover, unless you choose a read-access option.

Read access: RA-GRS and RA-GZRS

With plain GRS or GZRS, the secondary copies exist for recovery only: you can't read them until a failover makes the secondary region the new primary. Read-access geo-redundant storage (RA-GRS) and read-access geo-zone-redundant storage (RA-GZRS) let apps read from the secondary region at any time through a separate secondary endpoint, so reads keep working while the primary region is down.

Rosa: So RA stands for Really Available?

Dev: Read Access. But yours is easier to remember.

Exam tip Because geo copying is asynchronous, the secondary can lag behind the primary: the newest writes may not be there yet.

Picking one

Ask two questions. First, what must the data survive: a failed disk or rack (LRS), a whole zone going down (ZRS), or a regional disaster (GRS or GZRS)? Second, must apps keep reading it during a regional outage (add RA-)? More protection costs more, so match the option to the data. One catch: the archive tier works only in LRS, GRS and RA-GRS accounts, not zone-redundant ones.

Mr. Barkley: So the flood question has an answer. And a price tag.

Dev: Every answer in the cloud has a price tag. This one's worth reading.

AzCopy

AzCopy is a command-line utility for copying blobs or files to or from a storage account, or between storage accounts. Because it's a command, you can script it and schedule it. It can also synchronize in one direction, making the destination match the source; it doesn't sync both ways.

azcopy copy 'C:\exports' '<URL>' --recursive

Azure Storage Explorer

Azure Storage Explorer is a free standalone app for Windows, macOS and Linux with a graphical interface. You browse storage accounts like folders and upload, download or move blobs and files with clicks. Under the hood it uses AzCopy for transfers. Handy for people who'd rather not type commands.

Priya: That's the one going on the help desk laptops.

Azure File Sync

Azure File Sync keeps Windows file servers and an Azure Files share in sync, in both directions. The local server works like a fast cache: users keep their mapped drives and shortcuts. With cloud tiering, rarely used files are kept only in Azure and leave a pointer behind, freeing local disk space, while frequently used files stay local. You can sync several servers to one share, and if a server fails, just install File Sync on a new one.

Exam tip Two-way sync that keeps an on-premises Windows file server = Azure File Sync. Scripted copy or one-way sync = AzCopy. Point and click = Storage Explorer.

Azure Migrate

Azure Migrate is a hub for moving to Azure. From one place you discover what you run on premises, assess whether it's ready for Azure and what it would cost there, and migrate it. It covers servers, databases, web apps and virtual desktops, and it brings together integrated tools such as Azure Database Migration Service and Azure Data Box, plus partner tools.

Maya: Before we move anything, I want a list of what's still in Pawsome's back room and what it would cost in Azure.

Dev: That's Azure Migrate's first job.

Azure Data Box

When the network is too slow, ship the data. Azure Data Box is a rugged, encrypted device Microsoft sends you. Copy data onto it, ship it back, and Microsoft uploads it to your storage account. Current devices hold 120 TB or 525 TB (the older model held 80 TB); Data Box Disk covers smaller jobs. It also works in reverse, to export data out of Azure.

• One-time moves of lots of data, like media libraries or backups
• Sites with little or no network bandwidth
• Exporting data from Azure, for disaster recovery or a move back on premises

Sam: Sixty terabytes over our line: weeks. A box on a truck: days.

Exam tip Lots of data + slow network = Data Box. 'Discover and assess first' = Azure Migrate.