Rackable Systems S3118 User Manual page 11

power failure, consider adding "async" to your export options so that writes can be cached in system
memory prior to being written to disk. This can make an extreme difference in NAS write performance so
you should set this option if you can afford to.
For Windows clients, you will need to set up Samba and use it to export the file systems via CIFS
protocol. For more information on Samba, please visit the Samba web site at http://www.samba.org/.
5.3.5 Tuning Linux NFS Server Performance
One more performance optimization that is worth making for large file streaming application is to increase
the size of the data readaheads. Add the following lines to /etc/sysctl.conf:
vm.max-readahead = 256
vm.min-readahead = 128
Then type "sysctl -e -p /etc/sysctl.conf" to make the changes take effect.
5.3.6 Tuning Linux Client Performance
Optimizing the Linux-based server configuration is not sufficient to achieve the highest possible
performance. Doing so also requires client-side tuning.
The most important thing to test is varying different mount options. Try using NFS v3 over UDP with
RSIZE and WSIZE in your mount options set to "32768" for streaming environments. If your networking
infrastructure doesn't show excessive packet retransmits when using these settings you will achieve the
highest throughput rates this way. With some lower-end or older network switches the retransmit count
may be high enough that you may obtain better results with a 4K or 8K block size.
On the Linux clients, modify /etc/sysctl.conf as follows to improve large file single stream
performance:
net.core.rmem_max = 262143
net.core.wmem_max = 262143
net.core.rmem_default = 262143
net.core.wmem_default = 262143
Again, "sysctl -e -p /etc/sysctl.conf" makes the changes take effect.
5.3.7 Improving Availability Using Smartmontools Software
If your system uses 3Ware SATA RAID cards accessed in either hardware or software RAID modes, you
should consider installing the Smartmontools package (http://smartmontools.sourceforge.net) in addition
to installing and using the RAID card vendor's management package (described in the RAID
Configuration section above).
The Smartmontools utility provides a mechanism for running long integrity tests on individual hard drives,
even through a 3Ware card. This can be used to detect SATA drive problems that are likely to fail in the
future but have not resulted in a catastrophic RAID failure yet. Problematic drives can then be replaced
ahead of hard RAID failures in a more planned manner. By running these tests on all drives periodically
you can improve server and data availability quite significantly. Doing this on a weekly basis automated in
the server crontab makes sense for many administrators.
With this package installed, the "smartctl -t long -d 3ware,4 /dev/sda" command would start
an extended background test on a specific drive (in this example, the drive on port 4 of the first 3Ware
card).
To access drives on the second 3Ware card, you need to first determine any device name that resides on
the second controller card. Using hardware RAID and one RAID volume per card, typically you would
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