Storage Performance

Capacity  (GB or TB)
Performance(MBytes persec)
Throughput (I/O  persec)
Latency (Milleseconds)

7200 RPM SATA :80 i/o ps
10K RPM SATA/SAS/FC :1200 i/o ps
15k RPM SAS/Fiberchannel :180 i/o ps
SSD (Solid State Device) MLC :1000-2000 i/o ps
EFD (Entp Flash Drive) SLC Single cell Tech :6000-30,000 i/ops

VMFS filesystem in SAN,iSCSI,FC ;NFS filesystem in NAS.

Blocked Based Storage:-SAN Fiber Channel (1- 20 GB speed) or iSCSI (100MB to 10 GB speed)

File Based Storage:-NFS (100 to 10 GB speed)

VMFS is used on local SCSI, FC, or iSCSI SAN (but not NFS)

SIOC(Storage I/O Control) is only implemented from 4.1
This will allows us to allocate share on per VM basis so that VM can access Storage I/O according
to the share allocated to them.
When Storage I/O Control is applied to Datastore cobfigured to multiple ESX hosts accessing a same stroage array Storage I/O Controller make sure that VM get it allocated i/o share.

Stroage Performance Factors:-

1)Number of VM on LUN
2)SAN/NAS configuration-Caching,RAID level, and number of spindles on a LUN
3)VMFS or RDMS RDMS offer no better performce than VMFS in thick mode
4) VMDK thin or thick
5)LUN queue depth(howbusy the LUN on a storage Array
6)Storage Protcol being used.
7) Storage I/O control
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Storage Performance :-

1)Average Disk Read Rate and Write Rate in KBps/disk (disk.read.average and disk.write.average)

2)Disk.devicelatency.average,disk.kernallatency.average,disk.queue.latency.average,disk.totallatency.average

per disk in millisecs

3)Device latency shouldn't exceed 25 ms,
Kernel and  Queue latency shouldn't exceed 2 ms,
toal latency or command latency shouldn't exceed 27 ms

4)disk.commandsAborted.summation & disk.busRests.summation
Per disk number of commands aborted with Windows VMs,an aborted command will occur if the I/O command wasn't fulfilled in 60 seconds,by default
Any number > 0 indicates major storage I/O bottlenecks or physical storage issues

Esxtop:Davg(not exceed 25),Kavg,Gavg=dvag+Kavg(guest)total(not exceed 27),Qavg
u disk devices
F to change field
 
WWN :- 50:00:fn:jh:kj:th:kl First four 50:00 tell you the vendor name Qlogic,Emulex,CNA
CNA is only for FCOE.

VSAN is similar to VLAN .They Provide isloation between multiple logical SAN's exisitng
on  a common physical Platform.


Zoning : To ensure that a LUN that is required to be visible to multiple hosts in a cluster.

Port based Zoning :

WWN base zoning :

Each VMFS volume has a metadata file which contains information  about File locks.

SATP : SATP module handles path failover for a given  storage array and determine the failover

type for LUN.

PSP :Handles the actual path used for every I/O .

How do we know VMFS datastore is overloaded ?

Q-length  resxtop :U  stroage QUED colum

Profile Driven Storage : Works with VASA (Vspshere Stroage API for storage awarness )
prinicple behind profile driven storage simples allow vsphere admins to build
VM storage profiles that describe the specific storage attribute that a VM requires.

Vspshere 5 has a software ISCSI intiator.

Once the LUN is presented you have to go and create a VMFS datastore.


Expanding VMFS Datastore :

1)You can dynamically expand the VMFS datastore if you have space avalible in  LUN.

2)You can add extent if you do not have space in the LUN and then increase the VMFS volume

3)Each VMFS has a UNIQUE UUID

4)Choose keep exsisting signature if you want to mount the datastore copy without writing

a new signature only possible if the orginal is deleted or unmounted becoz of similar UUID


5)Choose Assign a new signature if you want to write a new signature onto the VMFS datastore

keep in  mind this operation is irrversiable .If you have resignaured the datstore containing VM's

you will likely need to reregister those VM's in the Vcenter Server since path is changed.


No-root Squash option will give full explicit read/write acess.