This video talks about FAST Cache overview, components, promotions, shrinking and expanding, and demo on Unity system.
Hello and welcome to the E MC video.
In this video, we will talk about fast cash for unity systems. Here is the outline for this video. In this video, we will start with an overview of fast cash and then the components of fast cash. After we will talk about fast cash promotions and the expand and functions in fast cash. Then we will demonstrate fast cash in unsphere and we will show where to find additional resources. Fast cash overview, fast cash is a large capacity secondary cache that is built on top of the flash drives in the storage system.
This secondary cache is located between the ramp system cache and the hard disk drives in the storage pools. Fast cash has the three main components. The flash drives policy engine and memory map, fast cache, flash drives are configured in red one pairs. Fast cash policy engine manages all IO flow which includes the movement of data into and out of fast cash. It also maintains statistics about the data access patterns on the system and determines when fast cash promotions and the cleaning operation take a place.
The policy engine is system defined and user cannot change these settings. Fast cache memory map maintains information about the state of the flash drives also tracks the content of the pages that are located in fast cache. A promotion in fast cash is based on 64 KP page data copied from the back end drives to the fast cash drives. For faster access, the system cache will check the memory map to see if a piece of data exists in fast cash.
If it does not exist in fast cash, it will read the data from hard drives and place the data into the system cache in the background. If the data has been hit multiple times, the data will be copied to fast cash for faster access. When the page is located in fast, there is no need to go to the hard drives to get the data. Now we will talk about shrinking and expanding fast cash unity, fast cash allows you to shrink and expand fast cash as desired. When shrinking fast cash, you can remove pairs of fast cash drives to reduce the number of the drives and fast cash shrink only allows you to remove all but two fast cash drives.
Expanding fast cash is the opposite process of in fast cash, expanding fast cash can be done by adding pairs of drives to fast cash up to the system maximum. Not here, you can only expand with the same disk type that you initially created when a shrink operation is started. Fast cash will block promotion from occurring all dirty pages which are data not copied to the hard disk drive will be copied from the drives being removed from fast cash to the pool drives. Once all dirty data is copied from fast cash drives being removed, the drives are removed from fast cash for expand.
It is the exact opposite process of a shrinking pair of the drives are added to fast cash to expand the fast cash capacity as the drives are added. Promotion will start to happen. Note here, both the expand and shrink operations occur online and can happen at any time. Now, we will walk through a demonstration in how to configure shrink and expand fast cache and unisphere. After you log in into unisphere, click the gear icon to go to the settings page, click ST configuration and then click fast cache. There is no fast cache configured yet in this system to create fast cache, click create in this current system.
The size of disk that is available to create fast cache is 400 GB. Select how many disks you want to configure for fast cash. In this example, we will select four discs. You also can enable fast cash for existing tools by checking this box. Keep the box checked and click next. Review all the information and click finish in the result page. It will show the steps in creating fast cache, close the wizard. Now you can see fast cash has been created with four desks. Now let's just start with the shrinking process. Click the shrink button in this page. It will show you how many numbers of disks you have for fast cash.
Here you have four discs. Click the dropdown menu to see how many numbers of disk you can shrink up to. In this example, you can shrink up to two discs. Click. OK. A warning message will show up saying the system must flush all data associated with diss being removed from fast cache. Click. Yes.
To continue, the job will be running in the background. After it's done, the number of disc for fast cash is too from the same page. We will perform expand fast cache, click, expand here. You have different number of desks you can add, we will add two disks, click. OK. A job will be running in the background after it's done, fast cash will have extra pair.
Thank you for watching unity video for additional resources. Please check the E MC unity fast technology overview, white paper that can be found at E MC online support.
