[Samba] suggestions for a "fast" fileserver - 1G / 10G

[Emmanuel Florac]

Le Sat, 22 Mar 2014 12:37:15 +0100 vous écriviez:

> I'm looking for some recommendations for a "fast" fileserver regarding
> the hardware you use.
> 

What is your disk subsystem like? What filesystem, with which mount
options? Any server I've setup in the past 3 years routinely achieve
110 MB/s with samba on GigE, 600 to 800 MB/s using 10 GigE. 

The very very most important option is :

1° don't ever use CFQ on a file server. Use noop or eventually
deadline. 

CFQ absolutely sucks wind on servers. CFQ is only good for workstation
use of rotating disks (it absolutely sucks with SSDs, too). On servers
with a hardware RAID controller, use noop. Using md raid, noop or
deadline may be better depending upon your workflow.

2° Then comes the hardware: your disk subsystem should be about twice as
fast as you want your network to be. To achieve smooth, 100 MB/s
throughput, aim for 200 MB/s disk speed. Any pair of modern drives
should come close, anyway. Any decent RAID controller (not HP smartshit)
should achieve 500 GB/s in RAID 6 with 6 or 8 drives.

3° the filesystem is important. Don't use ext3, it's slow as snails
crawling in molasses. ext4 is pretty slow, too.  If you want to get
closer to bare metal performance, XFS is the best choice unless you
need more than 25 ACLs per file.

4° filesystem options: if you have a RAID controller with BBU or like
to live dangerously, use nobarrier option or barrier=0.  Don't use
data=ordered (well, if you really want to use ext4 try not to tie its
short legs).

5° queue, read ahead options are very  important too. Default linux
options are all thought out for single, 2004-vintage ATA disks. They're
far from  optimal on modern hardware. They're even farther for RAID
arrays. Play with the nr_requests and read_ahead_kb options
from /sys/block/sdXX/queue . On modern RAID arrays, typical value I use
are

 cat /sys/block/sda/queue/nr_requests 
1024

 cat /sys/block/sda/queue/read_ahead_kb 
32768

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