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VMax Deferred Maintenance
We have "deferred maintenance" enabled on a VMax. I am not very familiar with this option. It is my understanding that with "deferred maintenance" enabled EMC will not come out and replace failed drives until there are 0 spares available for a particular drive type.
For example:
If I had 8 x 300GB FC spare drives and 2 x 300GB drives failed EMC would NOT come out and replace the failed drives because 6 spares are still avaliable.
If I had 8 x 300GB FC spare drives and 8 x 300GB drives failed EMC would come out and replace the drives because 0 spares are now avaliable.
Am I understanding this correctly? Can this theshold be changed so EMC for example replaces the drives when there are only 3 spares available?
d2dowling
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July 8th, 2010 16:00
I am glad to see this being reviewed again. Coincidentally I am in the process of reading "The Black Swan - The Impact of the Highly Improbable" by Nassim Taleb - http://en.wikipedia.org/wiki/Black_swan_theory.
After the previous discussions, our recommendation (which our clients have readily agreed to) has been to NOT enable deferred service. Allen W has a good point - `If there is no risk in allowing a "Zero Hot Spare available" state then why would anyone waste money on putting in hot spares in the first place?`
Following on from that, if `After very careful analysis it was found that the new process did not impose any additional risk` (quoting 2gnWoUR4Wl1186674120175), then why take the trouble to modify the microcode, so a `customer can chose (sic) to change the criteria from zero to one in which we call the spares out for replacement` ?
Anonymous
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July 22nd, 2013 11:00
Hi all,
My main concern regarding deferral service enable is more like in Latam we certainly don't have NBD parts onsite when they come from Franklin, usually parts onsite are 1/2 week since request.
And I'm talking Mexico, where is not that bad and have warehouses all around the country. Yet I know that at most we have no more than 10 disks of a given PN on each warehouse.
So, if we wait to go onsite to perform all spare disks replacements we have the risk of just using all available parts of a given region as there are boxes with 20/30 spares configured, to say the less. And being in the hypothesis that "there is no longer available spares" for a given disk type, waiting a week or so to have parts onsite highly raises the risk of a double disk failure.
Countries in NOLA and South Cone have even worst scenarios, there are countries where there is no warehouse at all.
At least for my given accounts, I don't think this happening, I'm turning off deferral service until we can grant logistics to have larger stocks and our team to have more available CSEs to assist when these urgent SRs for many spares trigger.
Something to consider. Have a great day ahead.
A-J1
49 Posts
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July 24th, 2013 08:00
Hi, I would like to clarify one point here, Deferred maintenance will not wait for the spare count ot go down to 0 before calling the CE for replacement....
There is a concept of covering spare, Every drive has a covering spare drive assigned to it, In case that drive fails, the covering spare drive will take its place, this is not a 1-1 mapping, Onec spare will cover multiple disks. When enguinity detects that any disk does not have any covering spare it will call home and generate an SR for the CE to replace all spare drives which are pending replacement.
There is an AutoPse script that runs on the service processor, whenever a drive fails the AutoPSE script collects the RMA information for the drive ie serial number, part number etc. This script check is deffered disk service is enabled and if all drives have covering spares.
lakaspalay
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December 11th, 2014 10:00
Agreed on A-J. The enginuity will dispatch a spare replacement task to the CE wherein the next covering space will not available for the disks.
In plain example, you have 8 spares drives with Deferred maintenance enabled..3 of them were Not Ready. Enginuity detects disks has no covering spare, it will make an SR and dispatch a CE to replace the 3 Not Ready spare drives. It will not wait till the threshold of zero or one drive left from the spare pool.