SUMMARY: Max sizes and numbers of partitions in DU 4.0

From: Mike Hudson <mjhudson_at_uwaterloo.ca>
Date: Mon, 03 Jun 2002 16:41:55 -0400 (EDT)

I *really* wanted to know the maximum *fileset* size under UFS (although I
said *partition* size -- see original message below) and number of
partitions.

Thanks to Alan Rollow for the follwoing ...

>The file system size limits are based on testing and real experience
>of people trying to use larger. UFS has the 128 GB size limit, though
>that's largely a testing limit. AdvFS has separate limits, which I
>think were beyond 128 GB in late V4. Some limited testing I did on
>a early (maybe field test) V5 system with a large array suggests
>UFS has other limits out beyond 512 GB. Just a hair under 1 TB
>certainly had problems.

>The limited on number of partitions is 8, though there are practical
>reasons for only using 7. Using LSM you can slice up a large space
>into an arbitrary (something large anyway) number of smaller volumes.
>The reason for only using 7 partitions is that to change the size or
>offset of a partition you have to open the disk with some other
>partition; to change A you have to use C, to change C, use A. The
>partition opened also has to start at disk LBA 0, where the disk
>label is. If you use 8 partitions, only one will be able to start
>at LBA 0 and you can't use it to repartition.

---
Alan also suggested looking at the Software Product Description on
the DU 4.0E CD-ROM. Unfortunately I couldn't find an exact number there.
In the end, my solution was to use AdvFS for this RAID.
Original message:
> I have a new 1 Tb RAID which I am trying to partition. My 
> system is a DS20E running Digital Unix 4.0E.
> 
> I remember reading somewhere (but can't find the reference) that the 
> maximum partition size useable by Digital Unix is 128 Gb. If so I can 
> just make this work by creating 8x128 Gb partitions.  On this board it was 
> stated that the maximum partition size under V5.1A was 1 Tb.
> 
> I have searched through Compaq documentation to clarify this but with no 
> luck so far. I would appreciate it if someone could confirm whether the 
> 128 Gb number  is correct for Digital Unix 4.0E. I would like to have some 
> smaller partitions for various purposes, and it seems that I am limited 
> to having only a-h i.e. 8 partitions max, so if indeed 128 is teh max 
> there is limited flexibility.
-- 
Mike Hudson
Dept. of Physics             Tel: +1-519-888-4567 x2212
Univ. of Waterloo            Fax: +1-519-746-8115
Waterloo, ON N2L 3G1         http://astro.uwaterloo.ca/~mjhudson

Received on Mon Jun 03 2002 - 20:40:25 NZST