opkcapital.blogg.se - What does clean disk signature mean in drive snapshot

If this same scenario targets a Windows Server Failover Cluster (WSFC) much of the process is still the same for detecting signature collisions. The result is a new disk connected which is based on a snapshot of a volume. The CDD then checks the signature of the disk and in the event that signature collision is detected and a new unique value will be created and the disk presented to the standalone server as a new volume. When using a standalone server or virtual machine a copy can be used without issue because there is logic in Windows Server via the Cluster Disk Driver (CDD) that gets notified through Plug-n-Play that a new disk has been added. The process of creating a snapshot does not re-signature the volume.Ī copy or volume can be used in two different scenarios as we will discuss below.

Just as it shows Snapshot 1 represents Volume 1 block-for-block.

The example below illustrates Volume 1 and Snapshot 1 which shows each have the same ID = 9A802B99. When creating a snapshot it creates a block-for-block representation of the original volume that includes the unique identifications. These unique identifiers represent the signature of a particular disk.

MBR uses disk signatures and GPT uses GUIDs (Global Unique IDentifiers). When taking a snapshot of a volume that has partition (MBR or GPT) it contains a unique identification. GPT – Global Unique IDentifier (GUID) Partition Table.Copy – A new volume which is created from a Pure Storage volume snapshot. Synonymous with volume.Synonymous with disk for purposes of this article. Volume – What a LUN maps to and provides a 512-byte-sector Logical Block Addresses (LBA) space for reading and writing data.

LUN – A Logical Unit Number used to identify a logical unit, which is a device addressed by the SCSI protocol or Storage Area Network (SAN) protocols which encapsulate SCSI, such as Fibre Channel or iSCSI.

Snapshot – A point-in-time representation of a Pure Storage volume.

Disk – Windows uses the term disk to refer storage objects in Windows Disk Management.

Before diving into the details I want to explain some terminology so we are all on the same page. Leveraging snapshots to create new volumes that can be used on the same host or other hosts is an important feature as it allows for business and deployment agility when creating dev/test environments, large UAT systems and just general database scale out scenarios.Ī question that comes up a lot is on the topic of creating new volumes that are based on volume snapshots that need to be mounted back to the same Windows Server Failover Cluster (WSFC).