Hi Ernie,
The seemingly odd behavior of LDEV 1 runs back to an old enhancement brought into 5.5 (IIRC). It consists of, among all MPEXL_SYSTEM_VOLUME_SETS, of always using LDEV 1 in last order when trying to allocate PERMANENT space. This has been done to make sure that ANY MPE system always has sufficient TRANSIENT space to boot. As a result, LDEV 1 of course has less PERMANENT space than the other system disks so it can harbour more TRANSIENT space, i.e. virtual memory (as correctly reminded by Denys).
The 95% PERMANENT and TRANSIENT space limit you quote are not a problem per se. MPE would never let you allocate a 100% PERMANENT limit. It will always make sure ANY disk used as LDEV 1 has at least 360,000 sectors, which are needed, IIRC, during boot time as permanent space. In theory, you could even stretch your LDEV 1 to, I think, something like 97 %, which would still be within MPE bounds or, more precisely, Volume Management. Any attempt to configure such a high PERMANENT space limit to something that does not provide at least the sacrosanct 360,000 TRANSIENT sectors needed during boot will result in an error 6 in VOLUTIL. This is NOT the 5.5 enhancement. IIRC, this feature of transient space conservation during boot is as old as MPE/XL itself, i.e. mid-80s. It was very useful at a time when the standard disk was the 7935, which was exactly 1,559,704 sectors in space. Hence the "traditional" 75% limit (a default config value, I think), which is close to 75 % of the size of the old 7935.
I wrote an article about that at the time I beta-tested 5.5. I'm now quoting from a 10-year old memory, with a few burned-out neurons since then. Please pardon the inaccuracies, if any. Gee, if I could only get my hands on my article !!!!!
Christian Lheureux
Directeur BU Infrastructure / Manager of IT Infrastructure BU
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> -----Message d'origine-----
> De : HP-3000 Systems Discussion [mailto:[log in to unmask]] De la part
> de Newton, Ernie
> Envoyé : jeudi 20 janvier 2005 20:35
> À : [log in to unmask]
> Objet : [HP3000-L] Transient space on drive 1
>
> Greetings,
>
> Along with security issues, Vladimir noted that there was
> too much transient space used on our drive 1. We utilize a
> mod 20 disk array, with drive one consisting of 2 4-gig
> drives. Here's what my DISCFREE shows...
>
> | Configured | In Use | Available |
> -----------+-------------------+-------------------+-------------------+
>
> LDEV : 1 -- (MPEXL_SYSTEM_VOLUME_SET:MEMBER1)
> Device | 16411488 | 11282640 ( 69%) | 5128848 ( 31%) |
> Permanent | 15590912 ( 95%) | 9946032 ( 61%) | 5128848 ( 31%) |
> Transient | 15590912 ( 95%) | 1336608 ( 8%) | 5128848 ( 31%) |
>
>
> My other drives show in-use transient space at zero or one percent.
> I've
> never really understood exactly what this means, and we have NO problems
> with performance. So...is this a bad thing? Should I be chastised?
>
> Thanks,
>
> Ernie
>
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