xfs + 100TB+ storage + lots of small files + NFS

[Marcin Sura <mailing-lists@xxxxxxx>]

Hi,

Friend of mine asked me about evaluation of XFS for their purposes. Currently I don't have physical access to their system, but here are the info I've got so far:

SAN:

- physical storage is from FSC array, thin provisioned raid 6 volume,Â

- volumes are 100TB+ in size

- there are SSD disks in the array, which potentially can be used for journal

- storage is connected to the host via 10GbE iSCSI

Host:

- They are using CentOS 6.5, with stock kernel 2.6.32-*

- System uses all default values, no optimization has beed done

- OS installed on SSD

- Don't know exact details of CPU, but I assume some recent multicore CPU

- Don't know amount of RAM installed, I assume 32GB+

NFS:

- they are exporting filesystem via NFS to 10-20 clients (services), some VMs, some bare metal

- clients are connected via 1GbE or 10GbE links

Workload:

- they are storingÂtens or hundreds of millions of small files

- files are not in single directory

- files are undek 1K, usually 200 - 500 bytes

- I assume, that some NFS clients constantly write files

- some NFS clients initiates massive reads, millions of random files

- those reads are on demand, but during peak hours there can be many of such requests

So far they were using Ext4, after some basic test they observed 40% improvement in application counters. But I'm afraid that those tests were done in environment not even close to the production (not so big size of filesystem, not so much files).

I want to ask you what would be best mkfs.xfs settings for such setup.

I assume, that they should use inode64 mount option for such large filesystem with that amount of files, but I'm a bit worried about compatibility with NFS (default shipped with CentOS 6.5). I think inode32 is totally out of scope here.

Any other hints for setting this stuff up?

Probably some recent OS/kernel would also help a lot, right?

Also, do you know any benchmark which can be used to simulate such workload? I've googled a lot, but there is quite short list of multi-threaded, small files oriented benchmarks. To be honest, I've found onlyÂhttps://github.com/bengland2/smallfile to be close to what I need. Any other alternatives?

BR

Marcin