Improvement: Filesystem permission check

##### ISSUE TYPE
* Improvement Request

##### COMPONENT NAME

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cloudstack-sysvmadm
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##### CLOUDSTACK VERSION
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N/A
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##### CONFIGURATION

N/A

##### OS / ENVIRONMENT
Cloudstack running on linux systems

##### SUMMARY
Check filesystem permission before upgrading systemvms

##### STEPS TO REPRODUCE

Currently, when issuing the cloudstack-sysvmadm script for upgrading the systemvms (or doing it manually), the process starts without any prechecks.
When there is somehow an issue with filesystem permissions, the new systemvm.iso cannot be copied to the new location. It would be a nice enhancement, when cloudstack had a health check or at least the cloudstack-sysvmadm script a permission check.

A newly introduced health check could continuously check some relevant cloudstack metrics, including the filesystem permissions and show a simple go/nogo somewhere in the admin ui. Or the simple way: a script or the modified sysvmadm script which checks first all storage paths for the correct rights.

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##### EXPECTED RESULTS

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##### ACTUAL RESULTS

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Inizia individuando l’entry point cloudstack-sysvmadm e il modo in cui rileva i percorsi di archiviazione prima di aggiornare le System VM. Esamina il flusso di aggiornamento esistente e determina i controlli delle autorizzazioni previsti e il comportamento in caso di errore. Il lavoro è completato quando lo script o health check scelto rileva autorizzazioni inutilizzabili prima che inizi la copia o l’aggiornamento di systemvm.iso.

Scritto dal modello di indicizzazione a partire dal testo della issue.