Some limitations exist when using the Easy Tier ® function
on Lenovo Storage V7000.
- The Easy Tier function
supports the following tiered storage configurations:
- Local (internal) Serial Attached SCSI (SAS) flash drives in
a storage pool with local (internal) Serial Attached SCSI (SAS) hard
disk drives (HDDs).
- Local (internal) Serial Attached SCSI (SAS) flash drives in
a storage pool with Fibre Channel-attached
hard disk drives (HDDs).
- External Fibre Channel-attached
flash drives in a storage pool with local (internal) Serial Attached
SCSI (SAS) hard disk drives (HDDs).
- External Fibre Channel-attached
flash drives in a storage pool with Fibre Channel-attached
hard disk drives (HDDs).
- To ensure optimal performance, all MDisks in a storage pool tier
must have the same technology and performance characteristics.
- Easy Tier automatic
data placement is not supported on volume copies, which are image
mode or sequential. I/O monitoring for such volumes is supported,
but you cannot migrate extents on such volumes unless you convert
image or sequential volume copies to striped volumes.
- Automatic data placement and extent I/O activity monitors are
supported on each copy of a mirrored volume. The Easy Tier function
works with each copy independently of the other copy. For example,
you can enable or disable Easy Tier automatic
data placement for each copy independently of the other copy.
- Lenovo Storage V7000 creates
new volumes or volume expansions using extents from the Enterprise
tier, if possible, but uses extents from the Nearline tier or Flash
tier if necessary.
- When a volume is migrated out of a storage pool that is managed
with the Easy Tier function, Easy Tier automatic
data placement mode is no longer active on that volume. Automatic
data placement is also turned off while a volume is being migrated
even if it is between pools that both have Easy Tier automatic
data placement enabled. Automatic data placement for the volume is
re-enabled with the migration is complete.
Limitations when removing an MDisk by using the force
parameter
When an MDisk is deleted from a storage pool with
the force parameter, extents in use are migrated
to MDisks in the same tier as the MDisk being removed, if possible.
If insufficient extents exist in that tier, extents from the other
tier are used.
Limitations when migrating extents
When Easy Tier automatic
data placement is enabled for a volume, the migrateexts command-line
interface (CLI) command cannot be used on that volume.
Limitations when migrating a volume to another storage
pool
When Lenovo Storage V7000 migrates
a volume to a new storage pool, Easy Tier automatic
data placement between the generic flash drive tier and the Flash,
Enterprise, or Nearline tier is temporarily suspended. After the volume
is migrated to its new storage pool, Easy Tier automatic
data placement between the generic flash drive tier and the Flash,
Enterprise, or Nearline tier resumes for the newly moved volume, if
appropriate.
When Lenovo Storage V7000 migrates
a volume from one storage pool to another, it attempts to migrate
each extent to an extent in the new storage pool from the same tier
as the original extent. In some cases, such as a target tier
being unavailable, the other tier is used. For example, the generic
flash drive tier might be unavailable in the new storage pool.
If
the automatic data placement is enabled in the new storage pool, pending Easy Tier status
changes are assigned after the volume completes its move to the new
storage pool. Although the status changes are based on volume use
in the old storage pool, the new status is honored in the new storage
pool.
Limitations when migrating a volume to image mode
Easy Tier automatic
data placement does not support image mode. No automatic data placement
occurs in this situation. When a volume with Easy Tier automatic
data placement mode active is migrated to image mode, Easy Tier automatic
data placement mode is no longer active on that volume.
The Easy Tier function
does support evaluation mode for image mode volumes.