> > The general rule is that RAID will speed up reads but slow down
> writes.
>=20
> On what RAID levels? RAID 0 speeds up both.

RAID 0 speeds everything up because there is no protection to compute.

Remember all RAID is software - but the 'normal' meaning of software RAID i=
s that it is the operating system that is doing the RAID work. Hardware RAI=
D means there is a dedicated processor on the drive controller that is doin=
g all the RAID work, making the disk array look like a single drive to the =
host operating system.

Then again you can have mixed systems where you have two RAID controllers, =
each running their own set of striped disks in RAID 5, and then the two con=
trollers are run in RAID 1 in the host operating system to give mirrored RA=
ID sets. This can have an advantage for disk read access speed under some c=
ircumstances.

Another trick with hardware RAID controllers is for them to have heaps of R=
AM on them as disk cache. This can make huge differences if the OS is runni=
ng database applications where there is a lot of R/W access in a limited ar=
ea of the disk. Having multiple mirrored disks can also make a big differen=
ce with this database software, one mainframe system I was involved with wo=
uld have great arrays of drives mirrored together, often 6 to 8 drives in a=
 single mirror of the key structure of the database if it was getting a ham=
mering.

If the IT department cannot help configure a system, surely there is a comp=
uting faculty with some profs who could give guidance, or recommend some br=
ight young things among their students who might give actual help in config=
uring (and you could probably pick up useful tips from them as well) ...



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