Consistency groups

Consistency groups makes sure that data is been replicated consistently
In other words data which is been written to set of lun will be replicated as point-in-time

Cache flushing techniques

Cache flushing methods

Idle cache flushing
Watermark cache flushing
Force cache flushing

If In general cache writes data to disk in small chunks  but the data which has to be written from the host end is very large then idle cache flushing cannot maintain LWM(low watermark level) in this situation watermark cache flushing kicks in

Watermark cache flushing try's to maintain cache between low and high watermark if It fails to bring cache below high watermark then force cache flushing kicks in disabling all write cache

Force cache flushing writes data to disk by disabling  all write cache till data in cache reaches LWM 
Only after then write cache is enabled

In the mean while data wot be written to cache and rather will be sent directly to disks resulting in low write performance

By default 
LWM - 20%
HWM - 80%

LUN Migration

Right Click on the source LUN and select migrate
and then select LUN dialog box appears.

Why LUN Migration ?

In order to overcome any of the these limitations LUNs are migrated

1. Speed
2. Performance
3. Capacity

LUN Assignment for two cluster nodes

Each cluster node can have single storage group

Create two storage groups assigned to same host
Add LUN to each storage group.

------------- OR ------------------

Create a storage group and map two nodes and LUN to that storage group.

Meta Creation

Base LUN + New LUN (Unassigned LUN)

Goto LUN Expand Wizard.

Choose the Base LUN.

Choose the unassigned LUN which has to be added to the Base LUN to expand.

Choose the type of meta.

Stripping - Takes time as the existing data has to be striped equally between two LUN's.
Concat - Just adds space on a fly.

Add New Server to Production

New Server coming into Production.

Get the Server cabled to the SAN Switches.

Install NaviAgent in the Server.

NaviAgent Automates Host Registration Process. In other words creates direct entry in Clariion Connectivity Status.

Create Zoning

Assuming alias of storage is already created
alicreate "server_hba1","WWPN"
zonecreate "server_hba1_storage1","server_hba1;storage1"
cfgadd "activecfgname","server_hba1_storage1"
cfgsave
cfgenable "activecfgname"

Ensure Host has been registered in Storage
goto connectivity status, right click on clariion and click connectivity status.

LUN Allocation Procedure

Create a RAID Group / Thin Pool if it is required.
Create a Storage group (Access Logix must be Enabled)
Accessing a Host to the Storage group
Bind a LUN from a RAID group / Thinpool & map it to Storage group.

Some Interview Questions on SAN which are most regularly asked !!!!

1. What is power path?
2. Power path CLI to manage disks
3. List power path policy
4. What is vault drive?
5. What is the PSM LUN?
6. Basic of Storage
7. Define RAID? Which one you feel is good choice?
8. Storage array used in DAS
9. Explain iSCSI login, fabric login
10. Advantage of migration from DAS to SAN
11. What is Meta Lun?
12. Explain Clarion architecture
13. Explain DMX Architecture
14. Explain Enginuity operation layers
15. What is hard and soft zoning?
16. Explain WWN
17. What is zoning and how to create?
18. What is VSAN and how to create?
19. Hardware models of Clarion
20. What is FCID?
21. Explain Navisphere / Symmtric Management console / ECC
22. Initialization of clarion array
23. Explain rule 17 in DMX
24. Why and how symmask, symid and symcfg are used in DMX?
25. Symdev
26. Explain about symcfg
27. What is SYMAPI?
28. Configuration change in DMX
29. What is VCMDB?
30. Can windows, Linux, Solaris share the same FA in DMX?
31. What is Snap view?
32. What is mirror view?
33. What is SAN Copy?
34. Explain Time finder and SRDF
35. Difference in iSCSI and NAS
36. What is IQN?
37. Explain SAN, NAS and CAS using devices used in these model
38. Difference in iFCP and FCIP
39. What is fabric?
40. What is RAID? Explain RAID3, RAID5 and RAID 1/0
41. What is Hot Spare Disk?
42. What are the bay in DMX-3
43. Version and model
44. Brief the symmetrix CLI command
45. Create storage group and add device into storage group in DMX.
46. Create Time Finder clone using Cli
47. Composite Device group
48. Create SRDF
49. What is iSCSI?
50. What is Disk Controller?
51. How does data got saved in case of stripping and incase of concatenation?
52. What is the minimum no. of disks required for RAID 5 and RAID 6?
53. Difference between time finder and clone?
54. What is SRDF R1 & R2?
55. What is the version of Symmetrix DMX4?
56. In 4-24 what do 24 mean?
57. What is fabric?
58. Importance of RAID6?
59. How many disk Failures RAID5 supports?
60. Importance of masking?
61. Different RAID Levels?
62. What is quorum disk and its importance?
63. How to manually restore failed paths in Clarion?
64. Flash drives in DMX4
65. What is LCC? Link control card
66. Storage provisioning in DMX?
67. Steps for zoning using CLI?
68. Describe SMCLI commands you have used
69. LUN, Base LUN and MetaLun?
70. Difference between HP EVA 5000 and 8000?
71. What is CMI? Clariion message interface
72. What are the I/O operations in clariion?
73. Use of SPs?
74. What is VMCDB?
75. What is Hyper?
76. What is device in DMX?
77. What is SAN kit?
78. Channel directors and disk directors?
79. What is global memory?
80. Difference between Emulex and Qlogic?
81. What is storage array in Clariion?
82. What is FCID?
83. What is F-LOGI and P-LOGI? How authentication happens?