When To Use SSD With SDS - Part 2

IzumoFS with SSD Part 2

When to use SSD with SDS Part 2

As I wrote in the end of previous post, I'll talk about cluster of file system here.

The cluster size of file system In enterprise NAS is fixed but with IzumoFS you can choose size of a cluster or even format type to use. For example, ifs file system which became default in CentOS 7 can choose cluster size from 512B to 64KB (IzumoFS works on CentOS).

Things to know about cluster size

Cluster size has following points you should be aware of.

If cluster size is small
Peromance overhead will increase due to lots of read and write.
If cluster size is big
Capacity overhead will increase because small files will be treated as size of the cluster size.

If you could adjust the cluster size by file types or file sizes then you can maximise storage capability. For example, for the big files, such as video or music, choose bigger cluster size. If the files are small like system related files, choose smaller cluster size.

Below are the relation between cluster size with page size which we covered in previous post.

Cluster size > Page size
It always writes data in multiple pages even the IO was the smallest amount. If you have few threads to handle this the performance will decrease.
Cluster size < Page size
Unnecessary data transfer will increase because SSD is not capable of overwriting data.

In short, match cluster size and page size and you will get best performance out of SSD.

When to use IzumoFS with SSD

Best part to benefits SSD features in IzumoFS is meta data filed. IzumoFS will divide files into data and meta data when saving it. There are no special node required such as meta data server or controller server so by adding nodes not only capacity increases but performance too will increase linearly.

Meta data is going to get many random accesses plus IzumoFS can configure cluster size of file system so you are able to configure the system parameter to make best match for SSD use. By making meta data stores to SSD, you can expect very high cost performance.

To conclude, by thinking both SSD and SDS including IzumoFS and how to configure those in many different condition, not only you can use any kind of hardware but you will be able to use the hardware effectively.

At last

Needs for SSD is now bigger than ever. But maybe, that SSD is not well tuned for your purpose. There are possibility that you may increase existing SSD by simple adjustment. So how about checking how your SSD is configured?

  1. Many distributed storage refer cluster as multiple node pool but which they creates but the term cluster used in this article means the minimum data unit that file systems handle when saving giles.


  1. When To Use SSD With SDS - Part 1
  2. When To Use SSD With SDS - Part 2
  3. When To Use SSD With SDS - Part 3