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This detailed how to guides to achieve high availability and performance on Debian and CentOS for accessing storage space at IBM DS8300 Data Storage Systems. Tested on Debian GNU/Linux 5.x Lenny 64 bits and CentOS 5.3 64 bits running on 8 cores blades, with Host Bus Adapters Qlogic and Emulex Light Pulse Fiber Channel in deployed systems at SERPRO. Observations showed that Debian Lenny had the best performance, for our app load profile and hardware at that date in 2010.     Also, there are listed a number of previously not clearly documented critical pitfalls to avoid. STUDY whole articles, hints, implications, and cited resources before planning your deployment. Every detail matters . Before start, you  must  have LUNs at IBM DS8300 storage configured for high availability and performance as explained at the article  How to configure maximum performance storage space for Debian GNU/Linux on IBM DS 8300 Data Storage Systems . Multipath and storage basic c

The IBM DS 8300 Data Storage Systems were multi millions dollars flexible high availability and performance SAN machines. But you may left much of such performance and availability behind if you do not configure them correctly for Debian GNU / Linux. See how to ask for performance data storage space on them. Or what you need to configure on them. Read about an actual configuration running with Debian GNU / Linux hosts at SERPRO. Essential concepts about IBM Data Storage performance The IBM DS architecture was born for mainframe use. So you need to understand some different concepts / naming from the Debian GNU / Linux regular ones. The IBM DS 8300 hardware and software (it is a multi cpu Power AIX machine) is  optimized for highly parallel I/O requests . The IBM DS 8300 hardware could be "logically partitioned" (LPAR) in order to guarantee quality service levels (space, latency, transfer speed) and LPARs could be grouped into Storage Facility Images (SFI) f

Thousands concurrent parallel read write accesses over tens of millions of small files is a terrible performance tuning problem for e-mail servers. You must understand and fine tune all your infrastructure chain, following the previous articles for data storage and multipath on Debian 5.x Lenny. We reduced the CPU I/O wait from 30% to 0,3% (XFS) and 5% (EXT3) with these combined previously undocumented file system tuning tips. Mainframes have excellent parallel I/O performance. Data storage systems could deliver parallel I/O performance to Debian GNU/Linux if you configure them , your multipath connections , undestand the concepts, application behaviour and follow some hints for confguring and tuning your LVM, RAID, XFS, EXT3. The key word is  PARALLEL . Fiber channel data storage systems, multipath connections, excell at parallel I/O. These days of multicore, multi gigabyte RAM, fiber channel and many channels gigabit connected Debian GNU / Linux systems serving thous