HP 3PAR disk replacement. How to deal with failed drive on 3PAR
This article treats of disk replacement on 3PAR for administrators who want to know a little more about the background of disk replacement.
3PAR logical layer
With telling about disk replacement on 3PAR, the logical layer cannot be omited, as this is the fundamental concern around hard drive replacement procedure on 3PAR. The logical layer of 3PAR consist few levels. In overall the structure is not complicated, starting with physical disk and ending on Virtual Volumes.
physical disks (PD) → logical disks (LD) → Common Provisioning Groups (CPGs) → Virtual Volumes (VV)
Physical disks are divided into chunklets, starting with 7000 series, we are talking about 1GB fixed size of chunklets. Then 3PAR is using chunklets to build LDs. This all happen without any administrator involvement. Chunklet is the basic logic unit in 3PAR terminology. Thanks to this approach, we are receiving nicely virtualized storage, with virtual RAID approach, which gives a lot of more flexibility, also in terms of redundancy. From the other hand, while some blocks within specific chunklet are unreadable, then the whole chunklet (1GB) is marked as failed.