Posts Tagged 'Cachecade'

February 5, 2016

Enable SSD caching on Bare Metal Server for 10X IOPS Improvements

Have you ever wondered how you could leverage the benefits of an SSD at the cost of cheap SATA hard drives?

SSDs provide extremely high IOPS for read and writes and are really tempting for creating volumes, which are IOPS centric. However, because SSD prices are significantly higher than SATA drives, IT managers are at a crossroad and must decide whether to go for SSDs and burn a fortune on them or stay with SATA drives.

But there is a way to use SATA drives and experience SSD performance using some intelligent caching techniques. If you have the right PCI RAID card installed on bare metal servers, you can leverage certain SSD caching feature benefits.

Make sure when configuring a bare metal server, which has sufficient drives bays (8+ the least), to have a LSI (AVAGO) MegaRAID card as the chosen RAID card. You can select the appropriate RAID configuration for OS and other workload data during the order process itself so that the RAIDs come preconfigured with them. As an additional resource for high speed cache device, consider ordering at least two or more SSDs. You can add this to your server even after deployment. These drives are the SSD caching drives that can be used to improve the overall performance of the cheap SATA drives from which one has carved out the volume. 

Install MSM for Easy Management of the RAID Card

Once the server is deployed, consider installing AVAGO MegaRAID Storage Manager (MSM) for the OS that has been installed in the server. (You can also perform a remote management of the RAID controller from a local machine by providing the IP of the server where the controller is installed).

Users can directly download MegaRAID Store Manager from the AVAGO website for the installed card in the machine. For the most popular MegaRAID SAS 9361-8i card download the MSM from the AVAGO website here.

How to Create CacheCade - SSD Caching Volumes and Attach to the Volume Drives

Follow these three steps to improve the IOPS on the existing Volumes on the bare metal server.

Step 1: Creating CacheCade Volumes

Once SSDs are deployed on bare metal servers and Regular Volumes are created, users can create a CacheCade volumes to perform SSD Caching. This can be easily achieved by right clicking AVAGO Controller and selecting the Create Cachecade – SSD Caching option.

Create Cachecade

Step 2: Choosing the right RAID Level and Write Policy for CacheCade Volumes

It is recommended to use a RAID 1 SSD Cache Cade Volume. This will eliminate a single point of failure at the SSD device level. This can be done by selecting available SSDs on the system and choosing RAID 1 as the RAID level. Click Add to add all available disks and Create Drive Group. Also, be sure to select Write Back as the Write Policy for increased IO performance for both Read and Writes to a Volume that needs to be cached. 

RAID Level and Write Policy for CacheCade Volumes

Step 3: Enabling SSD Caching For Volumes

If the Virtual Drives were created without SSD caching enabled, then this is the right time to enable them as shown below—selectively enable or disable set of Virtual drives which needs SSD caching.

Right click on the volume and select Enable SSD Caching.

Enable SSD Caching

Performance Comparison

We tried a simple comparison here on a 3.6TB RAID 50 (3 Drive with 2 Spans) volume with and without SSD caching using IOmeter tool (available here). The workload was a 50/50 (Read/Write) 4kb Pure Random IO workload subjected for about an hour on the volumes. 

Without SSD Caching – IOPS 970

Without SSD Caching IOPS 970

With SSD Caching – IOPS 9000 (10X Improvement)

With SSD Caching IOPS 9000 (10X Improvement)

The result shows a 10X IOPS and workload dependent benefit. Results also show how repeatable the Read/Writes are happening with the same LBA.

This could certainly help a database application or IO centric workloads, which are hungry for IOPS, get an instant boost in performance. Try this today at Softlayer, and see the difference!!

-Subramanian 

 

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