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Raid 5 on Proliant DL 380 G6

Messias Mandua
Occasional Visitor

Raid 5 on Proliant DL 380 G6

My Knowledge its not that high and Server Setup and configuration.

I have bought a new Server DL 380 G6, I have planned to Install Linux Sever on it.
I boot from the HP CD's and and it just gives me a option of creating arrays raid 0 & 1.
How do I go about it to create a raid5 solution?

Because when I create the array I'm not allowed to split the Disks in order to create a Raid 5 solution, please help

Messias
15 REPLIES
Viveki
Trusted Contributor

Re: Raid 5 on Proliant DL 380 G6

Hi

Please check whether you have the additional cache module that fits in a dedicated slot and adds support for RAID5. If it is not present the card will only support RAID 0 and RAID.
Messias Mandua
Occasional Visitor

Re: Raid 5 on Proliant DL 380 G6

Thanks a lot your answer was easy to follow.
One Question, can by any chance, the Disks can be accessed by the OS without creating any array?

Like this:
Array A with 2 Disks for Raid1 and the other disks, the rest of them, as normal disk i can go for Linux software Raid.
Its that possible?

Thanks for you time sir.
gregersenj
HPE Pro

Re: Raid 5 on Proliant DL 380 G6

You must configure the disks, for them to be available to the OS.

The good thing is, that you can create RAID 0 on 1 disk only.

Personally I would buy the battery, and get a HW RAID 5.
Messias Mandua
Occasional Visitor

Re: Raid 5 on Proliant DL 380 G6

Hi thanks for your replay!
Just a question, what do you mean with buy a battery? You mean a PCI card that supports RAD5, could you please advise me which one should i buy?

Thanks alot in advanced

Messias
gregersenj
HPE Pro

Re: Raid 5 on Proliant DL 380 G6

Sorry for the late reply, but I have been away and ill.

As Viveki wrote, You need additional cache/Battery to enable RAID 5 Support, on the the or some of the Smart Array Pxxx Controllers.

The Smart Array controllers do support RAID 5. But for some reason, you now need to have backup battery on the Cache for RAID 5 support to be enabled.
I can't tell you why HP has introduced this. On the Legacy Smart Array's, the battery was only required to enable write cache.

So what is this battery?
You got read cache and write cache.
On the legacy controllers, Compaq had a policy, saying, that they did not want to put customer data at risk. So for the write cache to be enabled, a battery had to be installed, to supply backup power for the write cache, so that the cache could hold the data, that wasn't written to the disks, in case of power loss. This battery was an option, that the customers who wanted it could buy it.
Over the years the battery has had many names, like Write cache enabler, BBWC (Battery Backed Write Cahce) and more.
In most cases, it's pretty much a rechargeable battery.
In a few cases it has been fixed to the cache module, so you would get a new cache module, when obtaining it.

On some, if not all of the Smart Array P models, the policy now, is that you have to install the battery to enable RAID 5.
My guess, is that HP want to increase the protection af your data.

What I'm telling you, is that the price for the battery is low, to get the feature, that you want.
A HW RAID is faster than a SW RAID, and don't put the workload on the servers CPU's.

I don't know aboute Linux, but with Windows you need to start the rebuild manually.
And if you got a failed disk 0, in a SW mirror, and a non hotswap disk, You need to know how to do it correctly.
And on HP-UX it's very complex.

With the smart array, you just replace the disk, and it will do everything for you.

Mike Schwager
Occasional Advisor

Re: Raid 5 on Proliant DL 380 G6

Yes yes yes! Buy the battery, and turn on the write cache! If your disk is busy at all, the difference is AMAZING! We have write await times (using iostat -x) that go from 300mS or more, to less than 100mS.

Make sure you install the ProLiant Support Pack and turn on the write accelerator. Assuming your RAID 5 is Logical Disk 2, do in Linux:

hpacucli ctrl slot=0 ld 2 modify arrayaccelerator=enable
hpacucli ctrl slot=0 modify dwc=enable forced # Drive Write Cache
hpacucli ctrl slot=0 modify cacheratio=50/50
Messias Mandua
Occasional Visitor

Re: Raid 5 on Proliant DL 380 G6

Hi gregersenj, hope you are okay by now! And thanks a lot for all of you! I will reading the HP manuals now in order to understand clearly all this. In fact what i have noticed its that our suppliers have no technical background on HP Servers.
So hope i will be in a position to workaround and solve this issue.

Just a simple question, do you guys think that i should apply for a HP course to understand all of this hardware issues?

All the best and thanks a lot.
Try to plan your holidays to Maputo, will be great...
gregersenj
HPE Pro

Re: Raid 5 on Proliant DL 380 G6

I'm well again, Thank you.

lack of knowledge, all ways generate more work.

I'm not sure, if you need to do training.
It all depends on what you need to do in the future.
If you are going to work a lot on proliants in the future, training is nice.
otherwise - read the manuals, and ask the questions.

Cheers
/jag
marcus1234
Honored Contributor

Re: Raid 5 on Proliant DL 380 G6

you need min 3 disks to create hardware raid 5

with 2 disks options are mirror and striping

assign points thanks enjoy :)
marcus1234
Honored Contributor

Re: Raid 5 on Proliant DL 380 G6

without backup battery for controller raid 5 is not possible ,,
Messias Mandua
Occasional Visitor

Re: Raid 5 on Proliant DL 380 G6

You're missing the last point!

Thank you. Now i know that i need a back battery.

Thanks a lot

MM
suresh A N_1
Occasional Visitor

Re: Raid 5 on Proliant DL 380 G6

hay thanks all i got my information thank you lot to team
alex_sun
Frequent Advisor

Re: Raid 5 on Proliant DL 380 G6

HP Smart Array P410i/Zero Memory Controller (RAID 0/1/1+0)
HP Smart Array P410i/256 MB Controller (RAID 0/1/1+0/5/5+0)
HP Smart Array P410i/512 MB BBWC Controller (RAID 0/1/1+0/5/5+0)
Available upgrades: 256MB, 512MB with BBWC, 512MB with FBWC, 1G with FBWC, Battery kit upgrade (for the 256MB cache), and Smart Array Advanced Pack (SAAP).
view you P410i
gregersenj
HPE Pro

Re: Raid 5 on Proliant DL 380 G6

You're welcome.

br
/jag
Doros
Occasional Visitor

Re: Raid 5 on Proliant DL 380 G6

We have a DL380 G6 with the P410i controller with an array configured with raid 1+0

We used to get decent performance with arrayaccelerator=disabled and the standard 256MB cache.
results with arrayaccelerator=disabled
"Throughput report Y-axis is type of test X-axis is number of processes"
"Record size = 4096 Kbytes "
"Output is in Kbytes/sec"

" Initial write " 199787.88

" Rewrite " 170505.25

" Read " 219632.55

" Re-read " 215411.47

" Random read " 155246.98

" Random write " 174302.49

iozone test complete.

We since installed a 1GB Flash backed cache and then did

hpacucli controller slot=0 ld 2 modify arrayaccelerator=enable
and
hpacucli controller slot=0 modify cacheratio=50/50

and re-run tests and we are now getting worst performance than before:

"Throughput report Y-axis is type of test X-axis is number of processes"
"Record size = 4096 Kbytes "
"Output is in Kbytes/sec"

" Initial write " 122697.71

" Rewrite " 141706.26

" Read " 251156.58

" Re-read " 251624.62

" Random read " 173504.79

" Random write " 139336.01

iozone test complete.


disabling the arrayaccelerator give back results similar to what we initially had:

"Throughput report Y-axis is type of test X-axis is number of processes"
"Record size = 4096 Kbytes "
"Output is in Kbytes/sec"

" Initial write " 186775.43

" Rewrite " 177908.39

" Read " 229871.85

" Re-read " 231672.25

" Random read " 162759.82

" Random write " 166722.18

Any ideas?