performance tuning a public mirror server - mike hulsman (proxy)

NLUUG 15 May 2014

Performance tuning a public mirror server

Mike Hulsmanmike.hulsman@proxy.nl

NLUUG 15 May 2014

My background

• Been a sysadmin since 1990

• Around 1995 started using Linux

• Since 2012 supporting ftp.nluug.nl

• Working @ Proxy in the Managed Services Team

NLUUG 15 May 2014

Hobby

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History of ftp.nluug.nl

• December 1992 – total download 448575834 bytes

NLUUG 15 May 2014

Former hardware

• 2 servers round robin DNS• All SCSI storage attached to 1 server• Storage exported with NFS and GFS

NLUUG 15 May 2014

Current Hardware

• 1 server• Xeon E3-1220 3.1 Ghz• 16 GB Memory• LSI Megaraid SAS 9271-4i• 4 x 1GB ethernet• 13 x 2TB disk, 12 disks in Raid5• 1 hot spare drive• 11 free positions for extra drives

NLUUG 15 May 2014

Performance servers 1 day avg

Max 480 Mb/sAvg 160 Mb/s2 TB/day

Max 800 Mb/sAvg 340 Mb/s4 TB/day

The current server

The 2 servers

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What we serve

• 17 TB of used storage• 13.800.038 files• 12.224.856 files smaller than 1 MB• 681.468 directories• 1.606.561 links (hard and soft links)

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Max of TB/month

Jun 2013 Oct 2013 Apr 2008 May 2013 Nov 2013 Feb 2014 Mar 2014 Dec 2013 Jan 2014 Apr 20140

20

40

60

80

100

120

140

93.67 94.61 94.66 96.43

103.94109.47

117.63 118.05 119.84

128.62

TB/month

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Atoptool with netatop

• Atoptool together with netatop kernel module•

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Mrtg

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Munin

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Nagios

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Design decisions new server

• Machine is I/O based not CPU or Memory• Disk I/O should be as fast as possible• 4 x 1 Gb ethernet cards in bonding mode• Is a public mirror server, downtime is not critical• Costs effective, whole server including disks costed about 5K

NLUUG 15 May 2014

Raid setup

• Machine build was in november 2012• Hitachi Ultrastar 7k3000 2 TB drives

– 2.0 million hours MTBF, 5 years guaranty– 64 MB cache

• LSI MegaRAID SAS 9271-4i Card– 1 Gb cache memory– CacheVault, NV Flash cache and battery

• 256kB Stripe size • 12 disks in Raid5 1 hot spare

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What was changed

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Problem #1

• 4 x 1Gb ethernet interfaces– Bonded as balance-alb

• Send and receive are bonded– Did not work out as we thought.– Maximum speed of all interfaces together did not exceed 960 Mb/s

• In June 2013 together with Surfnet assistance moved to 802.3ad and xmit_hash_policy=layer3+4– With atop we could see that the balancing is working– Did not work out as aspected– Maximum speed at that time was 993 Mb/s

NLUUG 15 May 2014

Solution

• Changes in the bonding parameters • Upgraded / downgraded ethernet driver versions• Tuning kernel parameters• Crap said the Surfnet engineer ;-)• Connection to a Cisco module where 8 ports have only a 1

Gb/s backend port.• We were on ports Gi9/3 Gi9/4 Gi9/5 Gi9/6• After rerouting ports (Gi9/3 Gi9/11 Gi9/17 Gi9/28) peaks of

2.4 Gb/s were seen

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The whole process of tuning

• At first I did not document, only implement– Now I document what I changed, including time stamp

• Buffers were too small• Timeout's were too long• Did not know where to start• So many performance tuning articles• The problem with a public mirror server is that it is public• I even changed parameters while writing this presentation

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Firewall

• Lot's of messages ip_conntrack: table full– net.netfilter.nf_conntrack_max = 1048576

• wc -l /proc/net/nf_conntrack– net.netfilter.nf_conntrack_tcp_timeout_established = 600

• Defaults are 432000 (5 day's)

NLUUG 15 May 2014

We can get troughput

NLUUG 15 May 2014

Networking buffers

• Ethtool -G ethx rx 4096 tx 4096• Ifconfig ethx txqueuelen 20000

– Also for bonding interface (not sure if needed)

• Ethtool -K ethx gso on (generic-segmentation-offload)• Ethtool -K ethx gro on (generic-receive-offload)

NLUUG 15 May 2014

Filesystems

• Limited to 3TB filesystems• Echo “noop” > /sys/block/sda/queue/scheduler

– Also tried deadline

• All are ext4– options noatime,nodiratime,noacl,commit=15

• LSI CacheFlushInterval=10 (default 5)

NLUUG 15 May 2014

OS level

• irqbalance to oneshot• Chkconfig –del cpuspeed; service stop cpuspeed• vm.min_free_kbytes=204800

– To prevent out of memory errors– Prevent deadlocks under high loads

• Ulimit – Max openfiles

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Yum-plugin-fastestmirror

• centos.mirror1.spango.com 1.624 ms • ftp.nluug.nl 1.533 ms• mirror.prolocation.net 1.44 ms• mirror.widexs.nl 1.371 ms

• Add “prefer=ftp.nluug.nl” to

/etc/yum/pluginconf.d/fastestmirror.conf

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Application level

• Rsync just the standards• Vsftpd just the standards• Apache 2.2.15

– Were running 4 instances, 1 for every IPv4 and Ipv6– Reduce now to 1 instance– KeepAlive On– MaxKeepAliveRequests 1000– ServerLimit 1024– MaxClients 1024– MaxRequestsPerChild 800

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Future

• Hardware– Memory from 16GB to 32 GB

• Add more opensource projects– Than we need more disks

• Nginx•• Maybe I should try XFS in the future• We just need more hits !!

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Some of the mirrors

• Most Linux distributions are mirrored (currently 163 different)• BSD (FreeBSD, NetBSD, OpenBSD• Openindiana, opensolaris, illumos• Jenkins• Mariadb• Vim• Blender, gimp, ImageMagick• Apache• Qt , perl, gcc• Vlc, xbmc, openelec

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• Questions......

• mike.hulsman@proxy.nl

• ftp-admin@nluug.nl

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List of URL's

• https://github.com/jeffmurphy/NetPass/blob/master/doc/netfilter_conntrack_perf.txt• https://gist.github.com/kfox/1942782• http://www.atoptool.nl/• http://www.bufferbloat.net/attachments/9/BufferBloat11.pdf• http://lwn.net/Articles/507065/• http://www.coverfire.com/articles/queueing-in-the-linux-network-stack/