MD1000 Configuration

Hi collegeguy,

 

  From hardware standpoint you might be able to use two channels on two controllers to stop the bus saturation. Also need to look at the IRQ situation in the server, if the RAID controller is sharing it's IRQ with another device that has heavy I/O needs, then you could be getting starved for IRQ servicing, and getting timeouts on the controller. Fix is to disable unused devices or to share the RAID controller's IRQ with a human interface device such as a mouse or keyboard.

 

warwizard

Doing 2 connections gives more bandwidth, but a single cable already gives you 1.2 GByte/s (not Gbit/s) between the enclosure and the raid controller. This is a whole lot of bandwidth and it's hard to 'fill' with a single server. Splitting the enclosure and connecting it via 2 connections may not help anything unless you somehow do manage to fill that whole 1.2 Gbyte/s bandwidth. Use something like perfmon to see how much (MB/s) IO you're generating.

What are you doing with the MD1000?

If you're running a database or something that's being accessed highly random, the best raid type is raid 10.

If you're using a raid 5 for Exchange or SQL or so, you may want to rethink your setup and change to raid 10.

It's hard to give more suggestions without more info like;
- OS?
- raid type?
- drive type (10k sas, 15k sas, 7200 sata)?
- quantity of drives in the disk group?
- what kind of data on the drives?
- write vs read ratio? (raid 5 is fine for highly read-oriented environments, but for high write environments, especially when of a very random nature (e.g. databases), raid 10 yields better performance)

The unit will be used as a file server for users, so lots of reading and writing....around 1,000 users.  From what you have said I'm now thinking we should configure it as RAID10?

 

We are purchasing a new server from dell to connect the MD1000 to..... would I be correct in thinking I should be adding a PERC6E?

 

The unit has 7 x 15k SAS drives in it, so I'm thinking about buying another 8 drives to max it out and configure it as RAID 10 as suggested.  If  do this, do I need to purchase anything else (i./e modules to split the backplane?).

 

Many thanks guys...your help is really appreciated!

Yes a perc6/E is the controller you'll need. Sorry, I thought you already had a server and were experiancing throughput issues. The other two connectors is so you can daisy chain additional MD1000's together.

  When configuring a RAID 10 you'll want the underlying RAID 1's spanned across from one side of the MD1000 to the other side, so the stripe will be contained entirely on one channel. This is a defense from a cable disconnect, you lose half the drives, but still have the array in degraded status and data continues to be accessable.

 

Regards,

warwizard

Sorry for adding another question to this thread....but our new kit has just arrived;

 

We have the 6e installed, and the MD1000 connected to it...fully loaded.

 

I'd like to configure this as suggested....i.e RAID 10, are there any instructions out there for doing this?