Upgrading Hot Spares

The general rule of thumb is to have 1 hot spare for every 30 disks.  The Navisphere manager help guide will show you how to configure a hot spare, this should be configured at the end of the enclosure (disk 14).

You can also review this white paper for best practices and high availability for CLARiiON and FLARE29.

There are several consideration around placement and binding LUN numbers of Hot Spares. For more information see  What are the criteria for global hot spare selection?

Like Todd siad, we normally put the HS in slot 14 of the DAE but it can really be anywhere in the system and it will still work.

To create a new HS,

Create a new Raid group and select Hotspare from the drop down.

Manually select the disk you want.

It should automaticaly bind the drive as a hotspare.

Glen ..isn't it the other way around ?

With newer flare versions you also must bind a LUN to the new hot spare raid group before you actually have a hot spare - the older flare was a one-step porcess.

glen

Thank you everyone.  I seem to have corrected it thanks to the great answers provided.  I wish I could tag more than one answer as the "correct answer" so I'm sorry if you only got a "helpful answer".

One thing I still am a bit fuzzy on, according to some of the rules of thumb, I should have one hot spare per encosure right?  Or I should have one hot spare per bus?  I'm wondering why when I created two hot spares for 55 disks ( I already subtracted the 5 for the head) that it sets both hot spares down on Enclosure 2, Bus 0.  I have 4 DAE's stacked, 0 thru 3.  Shouldnt I have to assign a hot spare to each bus?  Why are both hot spares on the same enclosure?

Thanks....

(I guess I will repost this as a fresh question)

Glen,  i think it is the other way around...  I like to place my HS in teh 200 RG range and also give it a lun ID of 200's but with the auto creation thing, i first make the RG, then delete the lun and recreate it with a lun# of my chosing.

AgeeTech

You dont need to have a HS for every shelf.  THe best practice is to have 1 hotspare for every 30 drives of a certain type.  The hotsparea re in that enclosure becuase that is where you selected the disk.  It could have been becuase those were the only free disks to select from.

Lets say all your 55 drives are the same (300G FC)  my recommendation would be to have 2 300G FC hotspares since you are close to the 60 mark.

I personally try to place  the hot spares on different busses while following the 30 drive rule. Other factors that could increase that ratio are drive size and drive type. The way the Hot Spare selection works is that when a drive fails the bus is searched for an available Hot Spare (HS) that meets the HS selection criteria. If there is not a HS, it is already being used or if the criteria is not meant then the search will move on to the next bus and continue until a suitable HS is located (assuming there is one). This all happens very quickly, like in milliseconds. So, if your HSs are all on the same bus it is okay.

The 30 drive rule is a best practice guideline based on research. I have had customers that have environments, like development where they are okay with assuming a higher risk and don't follow that rule. I have had customers that want a HS per tray because it is a HA critical environment. I have also had customers that keep their equipment in an environmental situation that is less than suitable and fosters a higher than usual drive failure rate. One such customer printed newspapers and the data center although in a separate room was located in the printing plant and exposed to chemicals, heat and unclean air.

Steps to create Hot Spare - flare 26 and higher - just tested on R26 array - with no Hot Spare LUN in the raid group that I created for the hot spare, a failed disk will not trigger rebuild.

1. Create new Raid Group, select Raid Type - Hot Spare

2. Bind LUN in new Raid Group, select Hot Spare - without the LUN, the Raid Group will not replace a failed disk

Older versions of flare - you could do this in one step, if I remember correctly.

glen