Raid 5 question

[rjnlinux]

I have 10 disks and I set up 2 volumes using Raid 5
so each volume has 5 disks allocated

Now Vol1 and Vol2
But we have only one raid controller card

will I face degradation in performance because I have a single raid controller card
I do understand that this is a single point of failure (having a single controller card)
but will my performance be significantly better if I have two controller cards
compared to single controller card

[Irithori]

Raid5 is not the raidlevel of choice for performance, so the question is kind of moot.
But to answer: Only if the number of operations exceed the controllerˋs capabilities you will see a degration in performance
Multiple raids increase the management tasks and operations, but so do a high number of disks an
of course the IO pressure generated by the OS and applications.

So, it depends on what hardware you have and what you do with it.
10 disks doesnt sound too many, if you have a decent controller like a hp smartarray p410 or similar.

[rjnlinux]

Raid5 is not the raidlevel of choice for performance, so the question is kind of moot.
But to answer: Only if the number of operations exceed the controllerˋs capabilities you will see a degration in performance
Multiple raids increase the management tasks and operations, but so do a high number of disks an
of course the IO pressure generated by the OS and applications.

So, it depends on what hardware you have and what you do with it.
10 disks doesnt sound too many, if you have a decent controller like a hp smartarray p410 or similar.

Thanks for your answer
To ask another question - You mention Raid 5 is not the raid level for performance
please suggest another Raid level

[Irithori]

Our DB machines have one p400 and two p800 smartarray controller, connected to 16 internal 146GB 15k drives and two jbods with 24 146gb 15k drives each

There is a raid1 for the system, multiple raid10 for the various db needs (db, temp, etc) and two raid5 for logging and db dumps
The raid10 is where the performance lies obviously.

[rjnlinux]

Our DB machines have one p400 and two p800 smartarray controller, connected to 16 internal 146GB 15k drives and two jbods with 24 146gb 15k drives each

There is a raid1 for the system, multiple raid10 for the various db needs (db, temp, etc) and two raid5 for logging and db dumps
The raid10 is where the performance lies obviously.

Yes...Oracle says SMART = Stripe and Mirror everything.
Raid 10 is the correct way to go...but our company does not want to spend a lot of money
and hence Raid 5 is what we get !!!

[Irithori]

Make a formal, written suggestion (email) nontheless.
If it getīs granted: good
If it getīs denied: Then you have something to point to, if someone complains about db performance.

[rjnlinux]

This is good advice ...to have it in an email

[Irithori]

There will most likely be a follow up discussion either in a meeting or in a mail thread.
If you are ignored, then your managers are either useless or not aware of the importancance of db machines.

Managers will likely try to get you to commit to goals with the lesser hardware.
This is part of their role. They need to identify real need and reduce costs.

Be sure you have numbers, monitoring metrics, IO performance data, db access patterns, etc ready to verify your claim.
Be aware of mind games: "It is your job to make it work on a budget, thatī s why you are here" or BS like this
Ask them, if their data (and possible customers) are not worth to invest in business class hardware.

in short: Have fun :P