Block Access Flashcards
SAN protocols
Hosts access LUNs and namespace by using the following connections
- FC
- iSCSI
- FCoE
- SAS
- NVMe/FC.
- NVMe/TCP
SCSI Protcols
SCSI = FC, iSCSI, FCoE
- FC is a protocol that transports SCSI commands inside a FC frame
- iSCSI is an IP-based storage networking standard that transfers SCSI commands inside a TCP data gram
- FCoE is a protocol that enables FC communications to run directly over Ethernet.
NVMe and NVMe over Fabrics (NVMe-of)
NVM Express, Inc. (NVMe) defines access protocols and architectures for connecting local nonvolatile storage to computers and servers
NVMe over Fabrics (NVMe-OF) is an extension of the NVMe protocol that defines how to use existing network protocols to transport NVMe.
Some NVMe-OF transports include NVMe/FC, NVMe/IB, RoCE, iWARP and NVMe/TCP.
NVMe/FC is the NVMe extension that defines and creates specifications for how to transport NVMe over FC
NVMe/TCP is the NVMe extension that runs over Ethernet and encapsulates NVMe command and data inside a TCP data gram.
(IWARP is a computer network protocol that implements remote direct memory (RDMA) for efficient data transfer over IP network.
All SAN Array
Offers symmetric active-active pathing, unlike FAS and AFF, which offer asymmetric active-active pathing.
Uses dedicated block-only storage protocols: iSCSI, NVME/TCP, FC and NVMe/FC (no NFS or SMB).
Is supported on NetAPP AFF A800, A700, A400, A250 and A220 HA pairs
Supports 8-node Metro Cluster IP configurations
ALL SAN ARRAY (ASA) key features
Reduced complexity - the simplified unified dashboard covers all required management.
Tuned for mission-critical applications - provide interrupted access to data during planned or unplanned failover
Scale-out ASA clusters - all paths are active and optimised across HA pairs
AFF-to-ASA in-place conversion - seamless conversion to change AFF to ASA clusters without migrating data (one way only).
All NAS protocols have to be removed before conversion is started.
ASA AND AFF cannot be mixed in a cluster yet.
Symmetric active-active host-to-LUN-access
All available paths are active and Optimized
When a path fails, reads and writes to the LUN continue over the remaining active paths.
When a controller is taken over the host IO resumes quickly.
Behaviour is consistent for both planned and unplanned takeovers
Host - ALUA and MPIO compatibility.
SCIS concepts
low-level block access to data
Highly efficient and requires less overhead than NAS
SCSI can provide a high level of resiliency
There is a relationship between an initiator, target and LUN.
iSCSI uses the SCSI protocols sent over TCP
SCSI commands
Frequently used commands include
Inquiry - used to discover attributes and capacities of logical unit and SCSI targets
Test Unit Ready - Reports whether a logical unit is ready for access
Report LUNs - Enumerates all available units on a given target port
Read - Provides the starting logical block (LBA) and length to read
Write - Provides the starting LBA and length to write
NVMe/FC or FC frames
Share hardware and fabric components
Can coexist on the same optical fibers, ports, switches, and storage controllers.
MVME replaces SCSI-3 command descriptor block (CDB) in an FC frame with the NVMe command set
NVMe/TCP data gram
No hardware is required
NVMe replaces SCSI-3 CDB in the TCP data gram with the NVMe command set.
NVMe Commands
Reduction from ~250 SCSI commands
A minimum of 13 NVMe commands
Only three IO commands
Substantial performance boost because of. (1) removed software locking (2) reduced context switches (3) streamlined commands (4) Increased Multithreading
IO commands - Read, write flush.
Admin commands - Create/Delete IO submission queue, Create/delete IO completion queue, get log page, identify, abort, set/get feature, Asynchronous event request
FC, iSCSI and NMVe naming (terminology)
FC - WWPN, LUN, igroup, ALU, e.g. wwpn 50:0a:09:85;87:09:68:ad
iSCSI - IQNC, LUN, igroup, ALU, e.g. Ian.1992-08.com.netapp:an.12345678
NVMe - NCN, namespace, subsystem, ANA, non.1992-08.com.netapp:5700:600a098000af4158
Steps to implement SAN
Implement using FC/iscsi - (1) verify license, (2) enable protocol on SVM, (3) create LUN, (4) create igroup and map lun, (5) discover LUN on host and prepare disk
Implement using NVMe (1) verify license, (2) enable NVMe protocol for SVM, (3) create namespace, (4) create subsystem to map name space, (5) discover namespace on host and prepare the disk.
Host utilities
Download Host utilities from NetAPP support
Depending on the OS features are - proper config of OS values, config of HBA values, documentation and Diagnostic tools
ISCI
Can be. Single node - direct attached, multi node - single network attached, multi node - multi network attached
Ethernet recommendations are Redudant connections (network, switch), use of VLAN, enabled Jumbo frames, LACP, QoS and NIC teaming on the host
Software initiator on the host creates the node name. On the storage the node name is created on the SMV when enabling the protocol.
Type - Date domain registered - domain name - unique name
Iqn. 1992-08. com.netapp: sn.a0123456789f:vs.1
E.g. iqn.1992-08.com.netapp:sn.a0123456789f:vs.1
