HOWTO: Multi Disk System Tuning

• Index
• Introduction
• Structure
• Drive Technologies
• File System Structure
• File Systems
• Technologies
• Other Operating Systems
• Clusters
• Mount Points
• Considerations and Dimensioning
• Disk Layout
• Implementation
• Maintenance
• Advanced Issues
• Troubleshooting
• Further Information
• Getting Help
• Concluding Remarks
• Questions and Answers
• Bits and Pieces
• Appendix A: Partitioning Layout Table: Mounting and Linking
• Appendix B: Partitioning Layout Table: Numbering and Sizing
• Appendix C: Partitioning Layout Table: Partition Placement
• Appendix D: Example: Multipurpose Server
• Appendix E: Example: Mounting and Linking
• Appendix F: Example: Numbering and Sizing
• Appendix G: Example: Partition Placement
• Appendix H: Example II
• Appendix I: Example III: SPARC Solaris
• Appendix J: Example IV: Server with 4 Drives
• Appendix K: Example V: Dual Drive System
• Appendix L: Example VI: Single Drive System
• Appendix M: Disk System Documenter

30. Appendix J: Example IV: Server with 4 Drives

This gives an example of using all techniques described earlier, short of RAID. It is admittedly rather complicated but offers in return high performance from modest hardware. Dimensioning are skipped but reasonable figures can be found in previous examples.

Partition       sda             sdb             sdc             sdd
                ----            ----            ----            ----
        1       root            overview        lib             news
        2       swap            swap            swap            swap
        3       home            /usr            /var/tmp        /tmp
        4                       spare root      mail            /var

Setup is optimised with respect to track positioning but also for minimising drive seeks.

If you want DOS or Windows too you will have to use sda1 for this and move the other partitions after that. It will be advantageous to use the swap partitions on sdb2, sdc2 and sdd2 for Windows swap, TEMPDIR and Windows temporary directory under these sessions. A number of other HOWTOs describe how you can make several operating systems coexist on your machine.

For completeness a 4 drive example using several types of RAID is also given which is even more complex than the example above.

Partition       sda             sdb             sdc             sdd
                ----            ----            ----            ----
        1       boot            overview        news            news
        2       overview        swap            swap            swap
        3       swap            lib             lib             lib
        4       lib             overview        /tmp            /tmp
        5       /var/tmp        /var/tmp        mail            /usr
        6       /home           /usr            /usr            mail
        7       /usr            /home           /var
        8       / (root)        spare root

Here all duplicates are parts of a RAID 0 set with two exceptions, swap which is interleaved and home and mail which are implemented as RAID 1 for safety.

Note that boot and root are separated: only the boot file with the kernel has to reside within the 1023 cylinder limit. The rest of the root files can be anywhere and here they are placed on the slowest outermost partition. For simplicity and safety the root partition is not on a RAID system.

With such a complicated comes an equally complicated fstab file. The large number of partitions makes it important to do the fsck passes in the right order, otherwise the process can take perhaps ten times as long time to complete as the optimal solution.

/dev/sda8       /               ?       ?               1 1 (a)
/dev/sdb8       /               ?       noauto          1 2 (b)
/dev/sda1       boot            ?       ?               1 2 (a)
/dev/sdc7       /var            ?       ?               1 2 (c)
/dev/md1        news            ?       ?               1 3 (c+d)
/dev/md2        /var/tmp        ?       ?               1 3 (a+b)
/dev/md3        mail            ?       ?               1 4 (c+d)
/dev/md4        /home           ?       ?               1 4 (a+b)
/dev/md5        /tmp            ?       ?               1 5 (c+d)
/dev/md6        /usr            ?       ?               1 6 (a+b+c+d)
/dev/md7        /lib            ?       ?               1 7 (a+b+c+d)

The letters in the brackets indicate what drives will be active for each fsck entry and pass. These letters are not present in a real fstab file. All in all there are 7 passes.