Re: How to organize oracle directories in Unix ?

• Joe Testa <teci_at_the-testas.net>

> It all depends on the underlying striping of the physical disks. I'm
> unfortunately constrained by raid 5 also, so my hands are tied when it
> comes to disk contention fixes, so i leave it to the unix SA to deal
> with it, i just end up with one huge logical filesystem and throw the
> datafiles wherever.

There is no reason that RAID5 has to cause you pain if the stripe size makes sense for your O/S (e.g., RAID stripe == disk I/O page).

Remember also that there are three layers to it: disks, RAID and LVM. Your RAID system probably exports each RAID group as a single physical volume (PV). You can specify which PV's each logical volume (LV) is assigned to -- if beer doesn't work try a cattle prod. This gives you the ability to manage contention pretty well.

Main problem I've seen is that EMC and friends sell 150GB drives, which get grouped into PV's at the raid level. This leaves you with a single "device" and no ability to plan the I/O at all (and, unfortunately neither booze nor prod's have worked with any managlement I've tried them on).

Even with striped LV's you can manage the I/O by choosing the LV stripe size sanely and perhaps striping across multiple devices.

--
Steven Lembark                                               2930 W. Palmer
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