[Samba] Samba performance

Linda Walsh samba at tlinx.org
Fri Jun 3 12:49:47 MDT 2011

Alan Hodgson wrote:
> On Wed, May 25, 2011 at 08:02:56PM -0700, Juan Pablo wrote:
>>> - 4 Intel Gigagit ethernet NIC ports with 802.3ad bonding connected to a
>>> switch configured tu use 802.3ad
>>> - 8 2TB 7.2 krpm SATA disks with hardware RAID5 (RAID stripe size 1024
>>> bytes, controller and disk cache enabled, readahead enabled)
>>> - XFS filesystem (created with the following parameters: size=64k -d
>>> su=1024k,sw=7)
>>> - Average file size in the share: 8 MByte
>>> - Gigabit network composed by Cat5E certified cabling and DLink DGS-3427
>>> gigabit switch.
> The way Linux does 803.ad is not really how you might expect.
> It's still not great though. You'd really be better off with a 10Gb/s interface 
> out to your switch if you need to guarantee multiple 1Gb/s connections over a 
> small number of simultaneous connections.
	Given my experience with bonded ethernet, I'd have to agree.  
	I'm 'just' waiting for the 10Gb prices to come down.  Still a bit 
out of reach for a home network setup.


su=1024k?!?   What raid controller are you using?   Usually 64K is usually
recommended for max performance.  But then above you say RAID strip size is
1024bytes?   There is a difference, no?  Which is it?
Either way: a bit off from optimal.

You want to set your log size to 32768b (not 64k; note: 32768b=128k).

For mount options, I have 'swalloc,largeio,logbsize=256k,nobarrier'.

Note, for nobarrier, you *should* have your system on a UPS, and a battery
 backup on the RAID controller's cache (LSI controllers have this, others
may as well).

Note, some perf-related options(from my smb.conf) (with host networking 
tuned as well), I have:
aio read size = 65546
aio write size = 65536
max xmit = 66576
min receivefile size = 65536
map acl inherit = Yes
server schannel = no
socket options = TCP_NODELAY IPTOS_LOWDELAY SO_SNDBUF=4194304 SO_RCVBUF=4194304
use sendfile = yes

Note: I'm not sure why my max xmit is > 64k, I probably had a reason
when I set it up -- not even sure if >64k is legal, it might explain why my
read rates are 6MB/s slower than my writes (119MB/s vs. 125MB/s) over Gb lan.

Those are MAX rates to a linear file -- NOT random small reads/writes, BTW....
Though I'll regularly see >50MB in random, with >100MB for large files.

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