From: Green, Simon (SGreen@KRAFTEUROPE.COM)
Date: Fri Oct 11 2002 - 13:33:26 EDT
You'll get some benefit because of sequential look ahead.
Have a look in the LVM Redbook; there's a section on this, I think.
Simon Green
Senior Technical Analyst
UNIX and AS400 Services
Philip Morris ITSC-E
Tel: +44 1242 284318
Fax: +44 1242 284510
-----Original Message-----
From: Holger.VanKoll@SWISSCOM.COM [mailto:Holger.VanKoll@SWISSCOM.COM]
Sent: 11 October 2002 18:13
To: aix-l@Princeton.EDU
Subject: Re: migrating a filesystem/lv from one disk to two disks
after doing some testing I assume the following:
1) If the lv is striped, aix-lvm will start the reads on all drives
simultaneously.
2) If the lv is only distributed among several pv, it will read the pps on
the first pv, and then read the pps on the second pv etc.
Its hard to find this out reliably by testing... I would be easier if there
were strip-sizes at 4mb (that would correspond to the pp-size)...
Thats why I am not sure here.
If I am right, that would mean that one gains nothing by this "poor-mans
stripe" in almost any cases.
Can anyone confirm my assumption? I am quite sure about 1) but not about 2)
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