To summarise in a traditional storage system each disk is dedicated to being a member of one RAID set, by using chunklets multiple RAID sets can co-exist on the same set of physical disks. a 450 GB disk would consist of 450 chunklets. For example there is a yellow RAID set made up of a data chunklet from the first 2 disks and a parity chunklet from the 3rd disk, real world there would be a lot more chunklets per disk i.e. In this simple example above we see 3 physical disks each with 4 chunklets per disk, each different colour represents membership of a different RAID 2+1 set. Let’s zoom in on a small number of disks to see how this looks. In a 3PAR system like in a traditional storage system RAID is used to combine multiple disks together but instead of using entire disks data is striped across chunklets. #3PAR COPY SPACE SERIES#Prior to the 7000 and 10,000 series the chunklet size was 256MB, the reason for the increase to 1GB was to reflect the growing size of disks. This is what happens in a 3PAR system, whenever a disk is added to the system it is divided into 1GB blocks of space called Chunklets. Over time Chunklet mellowed out, he realised hey it’s good to share and instead of demanding a whole disk to himself he was happy with 1GB of any given disk. This traditional and inflexible approach is shown in the diagram below: So on a traditional storage array to set up a simple RAID 5 2+1 set, you would need 3 disks, 2 data and 1 parity each of which was dedicated entirely to being part of that RAID set. He existed on a traditional storage array and since he didn’t get on with anyone he demanded a whole disk to himself. Things were not always so good for Chunklet, back in the day Chunklet was a bad dude with a bad attitude. Let’s introduce Chunklet, as its Chunklet that enables 3PAR to have a unique architecture and enable many of its capabilities. The perfect place to start is by looking at the 3PAR architecture, and specifically how 3PAR uses layers of abstraction to deliver a unique and flexible approach to RAID. The following command will set up a job to run weekly (Sundays, 0000 hours): createsched -no_alert "compactcpg -f -pat *" every January 1st, "0 0 1 1 the first day of every month, "0 0 1 * every Sunday, "0 0 * * every midnight, "0 0 * * every hour, on the hour, "0 * * * *"įor more details: Please refer the below link for HP 3PAR Command Line Interface Reference.I wanted to start a series of posts looking at 3PAR 101, a back to basics/ beginners guide to 3PAR. There is no significance of the task failure on the system. If it fails you may need to run it again. If there is any overlapping or parallel task running like AO, DO, or Tunesys, than the task may fail.Įnsure no paralelle task is running. Node: - This is a background low priority task and run when the system is idle. To Reclaim the Freed space on the CPG -R5, you can run the below command. Unless the -f option is specified,the command asks for confirmation before compacting each CPG. f : Does not ask for confirmation before compacting the logical disks. dr : Specifies that the operation is a dry run, and the tasks will not actually be performed. This option will not perform any region moves. trimonly : Removes unused logical disks after consolidating the space. waittask : Waits for any created tasks to complete. pat : Compacts CPGs that match any of the specified patterns. The compactcpg command consolidates logical disk space in Common Provisioning Groups (CPGs) into as few logical disks as possible, allowing unused logical disks to be removed and their space reclaimed.
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