Topic: Hardware RAID & Software RAID

[AlexG]

Hi Forum

One question: If I have a hardware Raid, do I have to setup SME at the beginning with the option noraid, that only the hardware RAID runs and not additionally the software RAID?

Best regards
AlexG

[jonic]

Works fine either way.

However I would recommend disabling the hardware raid, and using software raid. This way when one of the drives has failed you get an email warning you.

[idyll]

This is really not a well thought out reply.

Hardware RAID is easily monitored. In the most intensely used installations it is faster as well.

A generalized statement asserting SW to be superior to HW because of the built-in monitoring is just uninformed without first qualifying the user's needs and expectations.

regards,

patrick

[CharlieBrady]

Hardware RAID is easily monitored.

Software specific to the particular hardware will need to be installed and configured first. There is no software included in SME server for monitoring hardware raid, and no notification email will be sent.

In the most intensely used installations it is faster as well.

Please provide evidence for that statement.

[idyll]

I am fully aware of your extreme "like" of software RAID, and I am not going to try to go toe to toe with you. I am also not looking for a flame war. But the OP ask a valid question and I do not believe he received a balanced reply. I am not saying for a modest home system SW isn't a better solution.

I am saying software RAID has to share the systems bus, that means transferring the data from n number of drives across the PCI (whatever) bus while with hardware RAID it's all kept to the RAID card itself.

Sorry, I cannot share white papers or benchmarks to support my statement. You seem to be ready to really argue this point. Go ahead.


regards,
patrick

[CharlieBrady]

I am fully aware of your extreme "like" of software RAID, and I am not going to try to go toe to toe with you.

I don't have extreme anything. I just recommend doing the simplest thing possible, unless there is sound justification to do otherwise.

I am also not looking for a flame war. But the OP ask a valid question and I do not believe he received a balanced reply.

I believe that he gave a balanced and accurate reply, including a personal recommendation, which he backed up with a reason. You responded with, IMO, an unjustified accusation.

I notice also that jonic didn't assert that hardware raid was hard to monitor, nor did he/she make any "generalized statement asserting SW to be superior to HW".

Sorry, I cannot share white papers or benchmarks to support my statement. You seem to be ready to really argue this point. Go ahead.

I don't wish to argue the point. I just expect that when assertions are made about performance differences then they are backed up with evidence, not conjecture.

[m]

Please provide evidence for that statement.

When doing this one can get surprising results. These are the results of a bonnie++ benchmark I ran some time ago on SME7. In most tests the SW RAID is faster, but at a higher CPU load. Only in the 'Sequential Block Input' test the RAID controller beats the SW RAID.

Code: [Select]

Asus 1720E2 mit 3ware 8506-4 und SATA WD Raptor 36G 10000U/min RAID5 mit 4 Disks, 1GB RAM
--------------------------------------------------------------------------------------------
Version 1.03        ------Sequential Output------ --Sequential Input- --Random-
                    -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP
smeserver        2G 20888  65 20777   9 13372   4 23303  67 80467   9  338.5  0


Code: [Select]

Asus 1720E2 mit 3ware 8506-4 und SATA WD Raptor 36G 10000U/min Hardware-RAID off, Software RAID5 mit 4 Disks, 1GB RAM
--------------------------------------------------------------------------------------------
Version  1.03       ------Sequential Output------ --Sequential Input- --Random-
                    -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP
smeserver        2G 40121  99 40384  21 22570   9 26632  56 56801  10  460.4  1


[jonic]

One question: If I have a hardware Raid, do I have to setup SME at the beginning with the option noraid, that only the hardware RAID runs and not additionally the software RAID?

Works fine either way.

What I meant was:
- if you setup SME without selecting any special option you will get the following setup:
"1 Drive - Software RAID 1 (ready to accept a second drive)"
(http://wiki.contribs.org/Raid)

-if you setup SME with the option noraid you will not have software raid enabled at all.

[AlexG]

Ooops, I just asked a little thing. Please calm down and relax. Ok, I see it's up to me (us) what to prefer - both works fine.

Thank you for the informations.
AlexG