kevin@msa3b.UUCP (Kevin P. Kleinfelter) (07/19/89)
Why does AIX partition my lovely 300MB disk into "minidisks?" I understand the need for a paging minidisk (partition) and a dump minidisk (partition). Also, I can make a good argument for a separate root minidisk. The thing I don't understand is why have / /u /machinename /machinename/tmp /whatever-else-you-create-to-fill-rest-of-300MB Is there any reason why I should not just merge all minidisks except for root, paging, and dump into one "/usr"? You may reasonably ask, why do I care: Answer: If I have all my space in one partition, I'll never wish that I had given a greater percentage of my space to that partition! (P.S. If it matters, this is AIX PS/2 1.1.) -- Kevin Kleinfelter @ Management Science America, Inc (404) 239-2347 gatech!nanovx!msa3b!kevin
dyer@spdcc.COM (Steve Dyer) (07/20/89)
In article <672@msa3b.UUCP> kevin@msa3b.UUCP (Kevin P. Kleinfelter) writes: >Why does AIX partition my lovely 300MB disk into "minidisks?" >I understand the need for a paging minidisk (partition) and a dump >minidisk (partition). Also, I can make a good argument for a >separate root minidisk. The thing I don't understand is why have > / > /u > /machinename > /machinename/tmp > /whatever-else-you-create-to-fill-rest-of-300MB >Is there any reason why I should not just merge all minidisks except >for root, paging, and dump into one "/usr"? >(P.S. If it matters, this is AIX PS/2 1.1.) AIX RT doesn't require minidisks of the form /machinename. AIX PS/2 does, and both / and /machinename are implicitly mounted at boot time. This is undoubtedly an attribute of the yet-to-be-released TCF facility in AIX PS/2 and AIX 370, wherein a collection of PS/2s and/or 370's all share the same extended filesystem, including a common root. Files formerly found in /etc which are "private" to a particular machine have been moved to /machinename. On most UNIX systems these days, /tmp is a smallish partition of its own, and under TCF, placing it under /machinename/tmp makes sense, since having a global shared /tmp is risky, given that most UNIX systems presume that /tmp is private (e.g., composite filenames consisting of a string+PID will no longer be unique.) /tmp is a symlink to /machinename/tmp. Similarly, the per-machine files which used to reside on /etc (and elsewhere) are now symlinks to files on /machinename. TCF hasn't been released yet, but much of the code (and all of the design) to support it is already present in AIX PS/2 1.1. -- Steve Dyer dyer@ursa-major.spdcc.com aka {ima,harvard,rayssd,linus,m2c}!spdcc!dyer dyer@arktouros.mit.edu
dave@micropen (David F. Carlson) (07/24/89)
In article <672@msa3b.UUCP>, kevin@msa3b.UUCP (Kevin P. Kleinfelter) writes: > Why does AIX partition my lovely 300MB disk into "minidisks?" > > Is there any reason why I should not just merge all minidisks except > for root, paging, and dump into one "/usr"? > > You may reasonably ask, why do I care: > Answer: If I have all my space in one partition, I'll never wish that > I had given a greater percentage of my space to that partition! > It is rather obvious that this person was(is) IBM/VM/CMS damaged. :-) The reason for partitioning is several fold. 1) Large file systems make large lists that need to be traversed to find/ consolidate free space. Small file systems will be faster. (Speed) 2) Physical head motion can be reduced as a file cannot be spread across the entire disk. (Locality) 3) Dangerous file systems cannot corrupt important ones. (/usr/spool/news might grow without bound when deluged by another machine testing CNews. This overflow won't affect my precious data in my home directory because the file systems are completely decoupled.) (Decoupling) 4) A large contiguous file system, when damaged or obselete is harder to replace or workaround than several smaller file systems. (A 300 Meg file system is a bear to put onto several 160Mb drives when you get moved to a new system. Several 80Mb file systems can go anywhere with you. Plus your precious data isn't all over system dependent garbage. It is partitioned physically and logically.) (Maintainability) 5) Removable media make several filesystems that are interchangeable very easy. Of course, if everything is on one big partition, each pack must duplicate the entire environment. Put seldom changed files (/bin) onto permanent storage. Put fast changing but temporary (/tmp) onto the more permanent storage. Use removable file systems for only those files that need to be removed. It is seldom a good idea to put /tmp and /bin on removable media. So, partition sensibly and save yourself the hassle. (Interchangability) Any more? -- David F. Carlson, Micropen, Inc. micropen!dave@ee.rochester.edu "The faster I go, the behinder I get." --Lewis Carroll