Dell DX6000G Setup And Configuration Manual

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Copyright © 2011 Caringo, Inc.All rights reserved 20Version 2.6February 2011Appendix A. Temp and Logging Space ConfigurationEvery file that is written to or read from the DX Storage cluster will be cached in the locationspecified for the spooler directory during the installation process. The spooler directory is integralto the internal function of DX Storage CFS and should never be manually manipulated, particularlywhile CFS is actively running. Consequently, it is important that the directory be properly configuredprior to using CFS. The spool directory's file system should be configured with enough space tokeep the default maximum of 100,000 files and should be no smaller than 50GB. It must also belarge enough to hold 2X the largest data file being written. When allocating disk space, be sure toallow for adequate logging space if you selected to log to a file (max of 8 log files with 512MB each).In addition to the spool and logging space required for CFS, CNS maintains a lookup file in /var/lib.The size of this file will grow approximately 1Gb per 10 million files stored in the name space. Toensure there is adequate space for swapping of this file, 2Gb of free space must be available per 10million files written to the name space.If files in your system will be large, verify that the file system type will support sufficiently large filesand extended attributes. The mount option 'user_xattr' must be included in the /etc/fstab entry forthe spooler partition. Ext3 is recommended, although there are plenty of valid choices. A goodfeature comparison is available on the Wikipedia at the following URL: http://en.wikipedia.org/wiki/Comparison_of_file_systemsNoteIf you are using an Ext3 file system, the 'dir_index' option should be enabled by defaultbut should be verified for performance, particularly in situations where there are a largenumber of files per directory. To determine whether the option is already enabled, run thefollowing command:sudo debugfs -R feature /dev/sda1where '/dev/sda1' represents the disk partition where the temp space resides. If thereturned list contains a 'dir_index' option, no further action is needed. Otherwise you canenable this option using the following command, again replacing /dev/sda1 with the diskpartition where the temp space resides:sudo tunefs -O dir_index /dev/sda1If the available space on the partition where the spool/cache directories reside gets too low or thefile count exceeds 100,000, cached files with the oldest access dates will be flushed until adequatespace has been regained. If more than 65% of the available space for the configured partitionis utilized, the least recently used cached files are flushed until the cache is reduced by 10%.When 80% of available spool space is consumed, CFS will start returning out of space errors. Theevaluation of available space considers all usage for the partition, not just CFS usage, and includesany reserved space you have explicitly dedicated for other purposes. For this reason, best practiceis to configure a dedicated partition for the CFS spool/cache with a minimum of 50GB of availablespace. Environments writing large files under high throughput conditions may need to tune theircache eviction percentages to prevent rapid consumption of spool space and should contact theirsupport resource for further assistance.

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