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Why does an array expansion take so long ?

Max Fontana
Occasional Advisor

Why does an array expansion take so long ?

Hi there . My first post here . I've got a proliant ML350 with a 641 SCSI smart array and 3 SCSI 72Gb disks . I bought a fourth hard disk in order to expand my logical unit ( wrong calculation when I got it , I'm already in need of more space ! ) . I'm using Red Hat El4 . Installed everything for my server management . Launched the smart array config. utility . First step : expanding my array....24 hours needed !!!
Second step : expanding the logical unit : 22 Hours needed !!!???!!! Why did it take such a long time ? Ok , I must admit I'm a newbie to linux . I think I did something wrong but if not , why so much time ?
thanks in advance.
max ( Italy )
Igor Karasik
Honored Contributor

Re: Why does an array expansion take so long ?

Max, it is normal behaviour.
See "Array Configuration Utility User Guide"
page 24
"IMPORTANT: An array expansion, logical drive extension, or logical drive migration takes about 15 minutes per gigabyte, or considerably longer if the controller does not have a battery-backed cache"
You can add battery-backed cache to improve expanding time.
You can also change expand priority,
see page 21 in same document.