device creation failed

Question

i just tried to create 16GB raid 5 device using SMC .. but the device creation failed while preparing required resource. The error details logged in symapi log.. where can i find symapi log in SMC ?

bodnarg · Accepted Answer

The capacity you are listing is the size that you want the symmetrix device to be when you are all done. For Raid-5 it will create the required space on the 4 drives that it needs for protection (about 25% of the size)

The disk groups are something your CE could have created when he loaded your drives. Basically it is a logical grouping of drives that is typically used to help isolate workloads (i.e. maybe you put your tier 1 apps in one disk group and a data warehouse application in another disk group)

For configuration purposes it is a way to isolate on what set of physical drives your devices will be built.

As for the size issue in your next comment - not sure - check to make sure you do not have spaces or some other garbage in your input field.

dynamox · Answer

$Install_Drive\Program Files\EMC\symapi\log - on Windows/var/symapi/log - typical location for *nix

MarcT2 · Answer

On the host running Solutions Enabler (which could be the same machine as the SMC host), or could be a remote machine if you're using the SYMAPI server.

Anyway, the logs (by default) are in:
/var/symapi/log for unix
Program Files\Emc\SYMAPI\log on Windows

You'll need to look at the end of the most recent symapi- .log file.

Hope that helps!
Marc

wishtobeMrEMC · Answer

thanks for the info. since this is the first time i am creating sym dev using SMC, pls guide me ..

basically, i need to create 16 GB raid 5[3+1] device. I have chosen the option create device by right on clicking on dmx array. following inputs are displayed ..

Number devices :
configuration : [ raid 5]
emulation : [FBA]
capacity for each device : [i do know that it requires 4 devices to form a 3+1 raid 5 device. thus, should i enter 4xrequired cylinders to create a 3+1 device? and, what should be cyl size ?
disk group number: [ what is the group #?]

wishtobeMrEMC · Answer

Cylinders = GB / 15 / 128 / 512 then multiply result by 1024*1024*1024

with the above calculation, i have entered 18414 cylinders to get ~16GB . but , after entering # of cyl, it shows 17 MB as equivalent.

xe2sdc · Answer

For Raid-5 it will create the required space
on the 4 drives that it needs for protection (about
25% of the size)

I'd say it's exactly 33% of the size

The disk groups are something your CE could have
created when he loaded your drives. Basically it is
a logical grouping of drives that is typically used
to help isolate workloads (i.e. maybe you put your
tier 1 apps in one disk group and a data warehouse
application in another disk group)

DG are enforced by symwin when you have different drive types in your backend .. You must use 2 disk groups if you have both 146Gb@15K and 300Gb@10K ..
CEs usually tend to put new drives (added after initial configuration of storage) in brand new DGs to be able to "draw" new devices only on new devices without spreading hypers around. There are a lot of reasons for having different DGs in your binfile...

Not all as good as the one you mentioned .. but there are many

For configuration purposes it is a way to isolate on
what set of physical drives your devices will be
built.

As I said, just like our CEs usually do if you don't tell them what you DO want

xe2sdc · Answer

Somewhere (in Eng land) Kb is 1024 bytes (2^10) ... Somewhere else (in Sales land) a Kb is 1000 bytes (10^3) ... This is something like imperial and metric systems .. You have to translate and noone will ever change his mind

1 cyl = 960 kb

18414 * 960 = 17677440 kb

but if you round things too much and do your math like an Eng, the Sales man will understand you are talking about a 17 Gb drive

wishtobeMrEMC · Answer

DG are enforced by symwin when you have different drive types in your backend .. You must use 2 disk groups if you have both 146Gb@15K and 300Gb@10K

But, while forming a meta using SMC, is there anyway i can distinguish the device in a way which DG it belongs to. So that i can able to isolate workload between apps.

in the form meta screen, i dont see disk group info and disk the speed info. actually, we have created few disk groups based on disk speed.

bodnarg · Answer

I said about 25% - I was off by just 8%

Actually odd thing I've noticed that it really seems to get closer to 34% on Raid-5 (3+1) setups - must reserve some space or round-up on a cylinder boundary or something. Noticed this trying to create some SAVE devices for a DSE pool out of unused space and had to back into the right size for the device since it was not working out exactly on the 33% boundary.

wishtobeMrEMC · Answer

I have just tried to create 17GB Raid 5 (3+1) devices on disk group 1, which has lots of free spaces. But getting following error

The requested device(s) cannot be created because mirrors cannot be distributed according protection requirements
definition_error : CFGCHG_C_MIRROR_POLICY

please share your thoughts as always

RRR · Answer

When you choose to create some mirrors, the Symm needs enough space on physical spindels which are on different backend busses. This means that there might be enough space, but this space is not redundant available and therefor the create devs task fails.

wishtobeMrEMC · Answer

actually I am creating raid 5 3+1 devices , which will be created on 4 disks. mirror basically for raid 1 devices correct?

RRR · Answer

A mirror is indeed 2 disks yes, unless you're creating more than 1 symdev.

But still it must be something like that: each disk had 2 connections to a DA and AFAIK the numbers of those DA's should be in the rule of 17, so when conn 1 of a disk is on DA 5, the other is on DA 12. I must say I'm not a CE, so I'm not totally sure about this in modern DMX3's and 4's.

xe2sdc · Answer

The requested device(s) cannot be created because
mirrors cannot be distributed according protection
requirements
definition_error : CFGCHG_C_MIRROR_POLICY

The term "mirror" have a wide meaning in the error message. It refers to the hypers you bind to form a device. They may be 2, 4 8 or even 16 (if you use RAID6 14+2) slices/hypers that the code have to allocate somewhere on different drives/loops/processors to form your beloved device. Don't confuse "mirror" with "mirroring" or RAID1

xe2sdc · Answer

I suspect it comes from good old 4 mirror positions every symdev have

With RAID you use only 2 mirror position .. even while using 14+2. So the error still talks about "mirror policy" even if it's related to a RAID volume .. However it's good to hear you still try to open RFEs

Symmetrix

device creation failed

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