Increase the IO performance of big storage consisting of hard drives with the CacheCade feature with MegaRAID hardware controllers. Here are the commands to ensure adding an SSD to cache storage of hard drives and the whole output:
RAID5 of 3 hard drive. The name of the virtual drive is v0.
The CacheCade is in RAID0. The name of the virtual drive is v1.
The CacheCade is in WriteBack mode. The WriteBack mode is dangerous when the CacheCade device is RAID0, because there is no redundancy, but it’s OK if the purpose of the machine is just a proxy cache. WriteBack mode leads to much more performance to gain from the cache device over slow device sotrage, but should be carefully planned when using RAID0 cache (or single) device.
Using storcli – the cli command line tool to manage a (LSI) MegaRAID.
Add CacheCade RAID0 device by the first command. It will create a virtual drive RAID0 with the name v1.
Ensure the caching is enabled for the virtual device it should be by explicitly setting it with the second command. Adding only a CacheCade device may not add the cache virtual device to the existing virtual devices!
This article shows how to create multiple RAID 0 drives for each disk at once. For example, a controller with 4 disks using this feature you can create 4 groups of devices with one logical drive in it with RAID 0 type.
This is feature is a kind of HBA mode, but on steroids, because it uses the cache of the controller and the hardware controller (Smart Array) optimizations.
All of your disks and the space in them will be available to the OS, but through the Virtual Drive logic of HPE Smart Array. If you check out the article and why you may need JBOD here – Smart Array P440 – enable or disable HBA mode using Smart Storage Administrator it is mainly because of some file systems such as ZFS or Btrfs (even LVM and device mapper devices) have many more features than a hardware controller. So with this feature, you can easily have your disk “exported” to the OS and use the raid or more complex feature of ZFS, Btrfs, LVM, device mapper or another setup, but using the controller optimizations and cache. Be careful this setup could lead to much bigger risk of data loss on power outrages if write-back cache optimization is enabled. And the more complicated the file system (or device mapper) setup is the more problems it has on power outrages without battery unit back-up in the controller. Always use this feature with a healthy battery in the controller.
How to create multiple RAID 0 Virtual Devices on each disk attached to the controller at once:
STEP 1) Click on the controller “Create Arrays with RAID 0” on the left to create multiple arrays of type RAID 0 at once.
As a continuation of our series about HPE Smart Array P440 controller here how you can enable HBA mode of your controller. There are various scenarios why you may want to enable HBA such as:
JBOD mode -to use the disks in a sophisticated file system like ZFS, brtfs and more (or LVM, device mapper logical devices). You may have more features in the created logical device (or file system) – caching or managing the disks and so on
not using the cache (RAM) of the controller, so it may lower the risk of data loss caused by power outages
more platform independent when using software RAID / device mapper devices. When you create virtual drives in hardware mode, you must use only this type of proprietary controller or some compatible of the same company. When using software solution like software RAID or LVM (and the controller is in JBOD) you can move the disks with no problem to other hardware without the hardware controller.
* Some old controller (not this one) might have problems with SSDs such as timings when the disks start; when failing a disk (the SSD would probably fail with read-only, which means it could not be removed from the array and the metadata header cannot be changed to remove the disk); no TRIM support, which is essential for the disk endurance and many more.
After the screenshots, you can see the part of the Linux dmesg command with the lines related to the HP HPSA Driver and how the system sees the disks.
The following screenshots start with a controller in hardware mode in (HPE terms – Smart Array Mode), then enable the HBA mode, the OS will see the disks as JBOD and then again enable the hardware mode (Smart Array Mode):
SCREENSHOT 1) Click on the controller “Smart Array P440” on the left and then “Enable HBA Mode” to enable JBOD mode.
This article is to show you what different type of RAID logical drives and what strip size could be created on one Array consisted of multiple physical devices like hard drives or SSDs.
The following logical drives could be created or modified on Smart Array P440 with Smart Storage Administrator:
Multiple different RAID types with different strip sizes!!!
All RAID types could be modified and you could change the strip size to any type offered by the controller
Bigger RAID type logical drives could be change to smaller RAID type logical drives. Such as logical drives of RAID 5 type could be converted to RAID 0, RAID 1, RAID 6 with any strip size on-the-fly without losing your data. Read on to see all of the RAID type modifications you an make.
SCREENSHOT 1) Click on “Create Array” to create a new array.
This article is to show how to create RAID 1+0 in Smart Array P440 hardware controller and what kind of migration is possible from RAID 1+0 on this controller.
Existing RAID 1+0 could be migrated to RAID 0 or RAID 5 or RAID 6 (so the RAID Level transformation is possible) with different Stip size (any of the supported in the controller) on-the-fly with no data loss!
This article is to show how to create RAID 6 (ADG) in Smart Array P440 hardware controller and what kind of migration is possible from RAID 6 on this controller.
Existing RAID 6 could be migrated to RAID 0 or RAID 5 or RAID 1+0 (so the RAID Level transformation is possible) with different Stip size (any of the supported in the controller) on-the-fly with no data loss!