Device Deletion Question

Question

Hi,

I have an instruction to re-claim some storage from our VMAX that belongs to a server thats being taken 'offline'. I am familiar with the process and getting the devices un-mapped and un-bound. I am just not sure about the deletion and the possible impacts.

I know i could just delete the devices - 01F5 - 01FC (8 in total) and just note that these device id's are no longer in use. But what is of concern is that when we had the VMAX installed i sure i heard one of the engineers mentioning about trying not to delete too many devices as it leaves something behind? Not sure what exactly? Maybe some pointer to the device? Dont know really and that engineer has since left EMC so cant just try contacting him...

If the devices were a regular size i would just leave them and then mark them for use when a piece of storage work comes along requiring those size of devices. But because they are not this i think re-using them would be a miracle.

So i was just wondering how other people dealt with deleting devices and if there was indeed some best practice to avoid leaving behind any reference to the deleted devices that could over time impact the array?

Any views/info would be great.

Thanks

AndyACX · Accepted Answer

Thanks for that. Thats useful to know. I found that solutions document plus a couple of others and it makes sense with reagrds to filling the gaps. Just need to remember now that we need to check for them before new devices are allocated.

Thanks

dynamox · Answer

symdev -sid  list -all| grep ^[01234] | cut -c 1-4 > devlist
  
while read a
do
        if [ "x$b" = "x" ]
        then
                b=$a
        else
                g=$( echo "ibase=16; ($a - $b) -1" | bc )
                if [ "x$g" != "x0" ]
                then
                        echo "Gap found from $b to $a ($g devs)."
                fi
                b=$a
        fi
done < devlist

dynamox · Answer

Andrew,

take a look at this solution: emc212946

just like article mentions, you can fill those gaps by creating new devices that fill the wholes. You can run this bash script (can be easily convert to perl and run on Windows) and find how big are the gaps and then fill them with the symconfigure script. For example if this bash script found gaps 12,23,14 . You could fill them withing the script:

create dev count=12,size=230,emulation=FBA,config=RAID-5,data_member_count=7,disk_group=1;

create dev count=23,size=230,emulation=FBA,config=RAID-5,data_member_count=7,disk_group=1;

create dev count=14,size=230,emulation=FBA,config=RAID-5,data_member_count=7,disk_group=1;

VMAX

Device Deletion Question

Was this post helpful?