10k RPM drives VS 15k RPM drives

[Ben Knight]

I have a DL380 server that I am going to put some new hard drives in in a Raid5 configuration. I currently have 1 raid array that I am going to leave alone. It has 2 146gb 15k RPM drives in it.

I was wondering how much of a difference am I going to notice if in the second array I put 4 300gb 10k RPM drives in and setup raid5 on them...

Thanks!
Ben Knight

P.S. This thread ahs been moevd from Disk to ProLiant Servers (ML,DL,SL). - hp forum Moderator

[Sameer_Nirmal]

Hi,

Take a look at these docs for the reference.

http://www.seagate.com/docs/pdf/marketing/tp_547_fc_15k_nov2005_final.pdf

http://h18004.www1.hp.com/products/servers/proliantstorage/drives-enclosures/hotplug-ultra3/

http://wp.bitpipe.com/resource/org_1105453230_693/TP-543_OptimizingStorage_edp.pdf?site_cd=swsys&src=bpde_swsys_topics

[Shameer.V.A]

Hi Ben,
No problem.
It is better to have more lower capacity disks with higher rpm in a single array.

In your case you will have performance drawback on second array as your old array is of comparatively lower capacity with higher rpm hdd, where new array is of higher capacity with lower rpm disks.

You can make up the performance by increasing the number of hard disks , increase the cache memory on RAID controller, connect the hdds to different channels on RAID if possible.

Hope these informations will help you.

Regards,

Shameer

[Leif Halvarsson_2]

Hi,
The most significant difference will be the Random access performance (IOPS). You can expect about 30% increase with the 15k drives.

[Tom O'Toole]

As others have noted, I bet the raid5 array will be a bit slower, not only because of the rpm difference, but because the additional I/O required by raid5 will use up the benefits of 4 spindles vs 2.

When buying drives, check the price differential between 10k and 15k drives of the same capacity, sometimes it is a LOT. If you have the slots and the configuration that will allow it, you can usually get many more 10k drives. So for the same price, you can build a system that not only has more capacity, but is also faster, because of the increased spindle count. This is discussed in the eva best practices white paper, but I suspect it is more generally applicable.

[Hein van den Heuvel]

Please consider going Raid 0+1 instead of Raid-5 if you are at all concerned about performance and availability.
Your effective storage for the new unit will reduce from 900Gb to 600Gb, but is that a problem?

http://www.baarf.com/
http://www.miracleas.com/BAARF/RAID5_versus_RAID10.txt

Cheers,
Hein.