SOFTWARE-RAID-TIPS (was: Adaptec 7890 and RAID portIII RAID controller Linux Support)
Beau James
bjames at cisco.com
Mon Mar 22 00:02:57 PST 1999
--> >Part of the reason for this is that if you had one big array, then all the
--> >files on that array may be residing in the first portion of the disks. To
--> >seek from any one file to another could be a relatively short seek. When
--> >you split the filesystems, then a read of a file on each filesystem will
--> >result in a half disk seek to get from one filesystem to another.
--> >These half disk seeks will *destroy* your overall effective performance.
-->
--> OUCH!! This is VERY BAD news indeed :-( What you recommend is
--> virtually impossible. If you have several partitions to put in the
--> raid it'll cause an unacceptable loss of space... If you have to put
--> /, /usr, /var and /home in the raid, how many disks will you need?
Why bother breaking these directories into separate partitions,
especially if you are going to put all of them onto a RAID array?
Separate partitions is largely a historical artifact of *nix, based
on the limited size of disks. What is the benefit of perpetuating it?
Beau
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