we have several DELL R900 with PERC 6/E adapter in it. R900 using Redhat Linux.
Each R900 have two PERC 6/E adapter and at least two MD1000 connect to it.
Configuration 1:
PERC 6/E -- two MD1000
PERC 6/E -- empty
Configuration 2:
PERC 6/E -- MD1000
PERC 6/E -- MD1000
Normally first MD1000 for database and second MD1000 for nightly backup. My
co-worker told me there is NO difference on performance or battery life on botn
configurations.
I would like listen to your opinion on follwoing:
1. which configuration have better performance?
2. put two MD1000 on same PERC 6/E adapter will cause battery life shorter?
3. other comment?
Thanks.
On 01/10/11 5:41 PM, mcclnx mcc wrote:> 2. put two MD1000 on same PERC 6/E adapter will cause battery life shorter?raid batteries only get used when your power fails while the system is running, and are used to maintain the write cache so when power is restored any dirty data in the cache can be committed to disk. they should last for their shelf life, which is generally 5 years from date of deployment (I don't know Dell's spec on the Perc 6/E, I just mean in general). your other questions re relative performance should be tested with a simulation of your production sorts of workload, and other people's experience will have little bearing on your usage.
From: mcclnx mcc <mcclnx at yahoo.com.tw>> we have several DELL R900 with PERC 6/E adapter in it. R900 using Redhat >Linux. Each R900 have two PERC 6/E adapter and at least two MD1000 connect to >it. > Configuration 1: > PERC 6/E -- two MD1000 > PERC 6/E -- empty > Configuration 2: > PERC 6/E -- MD1000 > PERC 6/E -- MD1000 > Normally first MD1000 for database and second MD1000 for nightly backup. My >co-worker told me there is NO difference on performance or battery life on botn >configurations. > I would like listen to your opinion on follwoing: > 1. which configuration have better performance? > 2. put two MD1000 on same PERC 6/E adapter will cause battery life shorter? > 3. other comment?1. Depends on the PERC card... I guess the onboard cache will have to be 'split' between the 2 devices. Also depends on the motherboard layout maybe... Does each slot have dedicated 'bus speed'? Or do all slots have to share? 2. The battery has to hold long enough to write the cached data to disk... Since it the same amount of cache with 1 or more devices on one card, there should be no differences. 3. Why not just use configuration 2 if you already have the 2 cards...? JD
On Mon, Jan 10, 2011 at 8:41 PM, mcclnx mcc <mcclnx at yahoo.com.tw> wrote:> I would like listen to your opinion on follwoing: > > 1. which configuration have better performance? > > 2. put two MD1000 on same PERC 6/E adapter will cause battery life shorter? > > 3. other comment? > > Thanks.1. Configuration 2 will have better performance under high load. The PERC 6 is 3Gb/s per port. Each external connector has 4 x ports so you get 12Gb/s across all ports. 2. Battery life is just used to keep the PERC cache memory contents during a power failure. Ryan