DgName in symmir command, and what Raid level on EMC?

[Hanry Zhou]

I have a HPUX 11i server, and using EMC symmetrex disks. We have a SAN group who handles EMC, I'm just the system admin on this server.

1. where and how do I define the DgName in command of "symmir -g DgName...". This disk group name seems not related the volume group name in LVM. The command is shown in one of our backup script, but I could not find what DgName is"

2. If I assigned a EMC device (LUN) /dev/dsk/c0t4d0. Is there any way or command I can use to find out what Raid is this device configured? Is this raid5, or some raid else?

Thanks,

[Peter Weibbrecht]

Hi Hanry,

you can deterrmine the configured symetrix devicegroups with the command symdg list.
output looks like:

symdg list

D E V I C E G R O U P S

Number of
Name Type Valid Symmetrix ID Devs GKs BCVs VDEVs

box53-symgrp-1 REGULAR Yes 000xxxxxxxxx 5 0 5 15
box53-symgrp-2 REGULAR Yes 0002xxxxxxxx 4 0 4 0


You as Sysadmin have to create the groups on your box first.
see manpages for symdg and symld.

in short form:

you have to create the group:
symdg create -type [regular|RDF1|RDF2] DgName

Add the standard devices:

symld -g DgName add dev SYMDEV

SYMDEV is the hypervolumenumber of your Disk.
you can also try symld -g DgName add pd PdevName

PdevName is the spezialfile of your disk ( dev/rdsk/cxxxx )

You can attach BCV devices with symbcv...
Read the man pages, there are realy good.


you can find out the raid level of a symetrix device with the sympd list command or the symdev list command.

sympd list | grep c10t11d2

/dev/rdsk/c10t11d1 036E 01C:1 15B:D6 2-Way Mir Grp'd (M) RW 34526

2-Way Mir means raid 1 Mirrored device in the symetrix.
i don't have actually a symetrix with raid 5 ( i think EMC use raid S )

hope it helps,

Peter

[Hanry Zhou]

Thanks Peter for the response. Here is my follow-up question.

I used the command symld list | grep disk_name, and the result of that, I got 2-way's disk, so it is mirrored disk. However,
in our BCV implementation, we used symmir..split to split disks for the backup, and that split last for 12 hours. In this case, my question is what if a disk failed during the split? That will be no any protection.

I was told somewhere in the posting, saying BCV is actually 3-way's LUN. Is that true? and how can I tell?1
ways?

[generic_1]

By deault, a BCV is not protected and the frame luns are. So if your primary lun blows a disk, its ok, if your bcv blows a disk you have to have it replace, and remirror its gone. Yes it sucks.

Now on newer emc frames with newer firmware you can use what the call protected BCVs, but you will need more disks and this is a 1 + 0 mirror essentially so the overhead on disk space is high. The HP XP frames have a little more charming way of handing BCV data :) in basically a raid 5 fashion.

[Hanry Zhou]

If I have get the following output from the command "symld":
/dev/rdsk/c10t11d1 036E 01C:1 15B:D6 2-Way Mir Grp'd (M) RW 34526

Is this just simply two disks mirrored together , or a 1 + 0 mirror?

on bcv disk side, don't we have HA protection? What a about on primary side? Because after the split, both side will only have single disk withough any protection (if it is just configured as a two disks mirror). Am I right?

[Jim Mallett]

Regarding your first question, once the device group is created you would want to add a line to your profile:
export SYMCLI_DG=
This way you don't have to specify -g each time.

"Because after the split, both side will only have single disk withough any protection (if it is just configured as a two disks mirror). Am I right?"

The BCV and the mirror are different disk, so when you see the output "2-Way Mir" that doesn't refer to your STD and BCV, it refers to your STD and M1 (mirror). After a split your STD still has an M1 (mirror) and is protected.

JIm