Raid

I was fortunate enough to get to spend an hour with Dmitriy Sandler from Nimble Storage to see what all the fuss was about with their product and more specifically their Cache Accelerated Sequential Layout (CASL) File System. Hardware Overview Let’s cover some of the basics before we dive into CASL. The storage array comes fully loaded with all the bells and whistles, out of the box. All the software features are included with this iSCSI array and include items such as: ...

I recently got my hands on a pair of HP P4300s in the lab and wanted to see how the performance was with Network RAID. One of the most read posts on this site is on Understanding RAID Penalty and I was curious to see how Network RAID played into this equation. Basic Setup I have 2 HP P4300s, each with eight 15k SAS drives in a RAID 5 configuration. This means that I should have a total of 1400 RAW IOPS (8 disks * 175 IOPS) on each lefthand node. Since I have 2 of them, I’m calculating 2800 RAW IOPS. In order to get some real world functional IOPS, we’ll assume that we have 50% Reads and 50% Writes, and don’t forget to take out the RAID Penalty for the RAID 5. Let’s plug this into our Functional IOPS equation to get: ...

Determining which type of RAID to use when building a storage solution will largely depend on two things; capacity and performance. Performance is the topic of this post. We measure disk performance in IOPS or Input/Output per second. One read request or one write request = 1 IO. Each disk in you storage system can provide a certain amount of IO based off of the rotational speed, average latency and average seek time. I’ve listed some averages for each type of disk below. ...