Posts on hard drives, SAN technologies, RAID, SSD and similar. The most recent articles are on the top.

Windows SAN Policy

How the SAN Policy in Windows work if a VMFS datastore is presented to a Windows server.

The write penalty of RAID 5

Why each write causes at least four disk IOs and decreases write performance in RAID 5

How RAID 5 actually works

How the parity calculations are done with RAID level 5

VAAI – part 1 – optimize the Storage Array

How the VAAI clone block primitive could improve performance on an iSCSI network.

VAAI – part 2 – verify the support for VAAI

Learn how to verify if VAAI is supported on the SAN.

VAAI – part 3 – monitor VAAI in action

Verify that ESXi 5 storage offload VAAI is actually used with ESXTOP or RESXTOP.

VAAI – part 4 – SCSI Unmap removed in ESXi 5

The support for aid with Thin Provisioned LUNs is removed in latest update.

Windows Performance Monitor and Disk IO monitoring

How to monitor disk performance in Windows Server using the perfmon tool.

Storage performance: IOPS, latency and throughput

Explains the factors involved in the performance of mechanical hard disks.

The Windows quick and full format options

Watch out for Windows 2008 and R2 doing non-quick formats together with Thin Disk provisioning.

Creating a virtual iSCSI target server

How to setup a free iSCSI target server running in a virtual machine.