The following post
contains a few brief notes compiled from a day at the start of the month. Whenever I
have attended an event, completed a project... post-event and when time is permitting,
I like to review the things I should have known, things I need to remember
better, things I have learnt, and find answers to questions raised. Enough waffle – on with the notes!
Understanding the
role of NVRAM with NetApp Controllers
Source – https://communities.netapp.com/thread/13289
and Eugene Kashpureff
“In a single head
environment all of NVRAM is utilized to log write operations. NVRAM is split
into two pages - p0 and p1.
In an HA Pair the NVRAM on each member is
split, and all writes are logged on the local and partner NVRAM, for both p0
and p1.
NVRAM is good for
about three days.”
“Data ONTAP uses
NVRAM to log network transactions as a data integrity measure. In case of a
system or power failure, Data ONTAP uses the contents of NVRAM to restore
network data to disk.”
Understanding
MetroCluster
“NetApp provides a
"MetroCluster" option, that uses "SyncMirror" to provide a
geo-cluster or active/active cluster between two sites up to 160 km apart (DOT
8.1.1 – previously 100km.)”
A MetroCluster consists of two controllers – one controller
in Site A, the second controller in Site B.
Synchronous Replication introduces latency, see http://cosonok.blogspot.com/2012/12/synchronously-mirrored-sans
Right Sizing
“Disk drives from
different manufacturers may differ slightly in size even though they belong to
the same size category. Right sizing ensures that disks are compatible
regardless of manufacturer. Data ONTAP right sizes disks to compensate for
different manufacturers producing different raw-sized disks."
Flash Pool
Flash Pool allows you to cache both random reads and
random writes.
Controller
Failover Considerations for NFS and CIFS
NFS if a stateless protocol
CIFS is a stateful protocol
Source – Active/Active Controller
Configuration Overview and Best Practice Guidelines (PDF from 2007)
“For clients or
applications using stateless connection protocols, I/O requests are suspended
during the takeover/giveback period, but can resume when the takeover/giveback
process completes. For CIFS, sessions are lost, but the application may—and
generally will—attempt to re-establish the session.”
DTA2800 Data
Transport Appliance
The DTA2800 can be used for offline and online data migration over Fibre
Channel and iSCSI, from legacy storage to NetApp storage.
Image: DTA2800 and
NetApp Data Migration Service
Migrating CIFS Data
In a scenario where you want to consolidate many Windows
Fileservers, many of which have the same share names, leverage NetApp MultiStore!
“MultiStore
provides secure multi-tenancy capability to the NetApp Data ONTAP® operating
system, allowing you to:
> Host multiple
customers and/or departments on a single Data ONTAP storage system
> Consolidate
many file servers, thus reducing cost and increasing staff productivity
> Perform simple
and fast data migration
> Simplify your
disaster recovery strategy”
Migrating
Exchange Data
Typically migrating Exchange data is a case of enabling circular
logging (so the transaction logs don’t balloon in size) and performing
migrations. With NetApp you can leverage SnapManager for Exchange and take
regular snapshots whilst migrating the Exchange data so as to keep the
transaction logs down in size, whilst at the same time protecting the data
being migrated, and not requiring store restarts to enable/disable circular
logging.
Migrating
Oracle Data (on Red Hat)
With Oracle Data on say Red Hat Enterprise Linux, an
option for migration from legacy Fibre Channel storage is to migrate to NFS.
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