Azure Data lake Gen 2 Suggestions
Ø For blob storage, you organize a
set of files/blobs under a container. In the Azure portal this is located in
“Containers” under “Blob service”. It is called “Blob Containers” in both the
portal and desktop Storage Explorer. For ADLS Gen2, you also use containers,
located in the portal in “Containers” under “Data Lake Storage”. It is called
“Blob Containers” in the desktop Storage Explorer but it is called “File
Systems” in the portal Storage Explorer
Ø In the Azure portal, for blob
storage, you can upload/access files by going to the storage account and
choosing Containers (under “Blob service”) or by using the Storage Explorer
(preview) in the portal. For ADLS Gen2,
Containers (under “Data Lake Storage”) has no functionality except to create a
container (click “File system”), but you can use the portal Storage Explorer.
However, that is limited (you can’t upload files or change access tiers), so
you should use the desktop Azure Storage Explorer to upload files or change
access tiers
Ø There are two types of storage
performance tiers: Premium and Standard. The Premium performance tier can’t be
changed to the Standard performance tier and visa-versa, so this is locked in
when you create the storage account
Ø The Premium performance tier is not
yet available for ADLS Gen2, and only supports locally redundant storage (LRS)
Ø There are three types of storage
access tiers: Hot, Cool, and Archive. You can change access tiers with the
Standard performance tier, but not with the Premium performance tier. Only
block blobs support access tiers
Ø When creating a storage account,
you will be asked for the Account kind and you should use the default of
General purpose v2 (StorageV2) unless you want to create block blobs or append
blobs with the premium performance tier in which case you should choose Block
Blob (BlockBlobStorage). Note that BlockBlobStorage accounts don’t currently
support tiering to hot, cool, or archive access tiers
Ø A storage access tier can be set
for each file, but if it is not set it will default to the access tier (Hot or
Cool) that the storage account is set to. The account access tier is the
default tier that is inferred by any file without an explicitly set tier. The
Archive access tier can only be set at the file level and not on the account
Ø For blob storage, you can specify
the access tier for a file (hot, cool, or archive) when uploading via the
portal, but not when using the desktop Storage Explorer. For ADLS Gen2, there
is not a way to upload files via the portal and you also can’t specify the
access tier when uploading via the desktop Storage Explorer
Ø For blob storage, to change an
access tier, in the Azure portal, under the storage account, go to the
container and choose the file and click “Change tier” to change its access
tier. Or go to the portal or go to desktop Storage Explorer and right-click the
file and choose “Change Access Tier”. For ADLS Gen2, you must use desktop
Storage Explorer to change the access tier
Ø For blob storage, you can specify
that the blob type of a file is block, page, or append when uploading the file
via the portal or with desktop Storage Explorer. Once a file has been created,
its blob type cannot be changed. ADLS Gen2 only supports block blob type
Ø Data in the Archive tier blob
cannot be read until it is rehydrated to the Cool or Hot tier. The “standard”
rehydration process can take up to 15 hours to complete. There is a priority retrieval (called “high”)
that takes less than an hour (see Azure Archive Storage expanded capabilities:
faster, simpler, better). You specify
the rehydrate priority (standard or high) when choosing to switch from the
archive tier on the portal. The option to choose the high priority retrieval is
not available in the desktop Storage Explorer and is not available anywhere for
ADLS Gen2
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