Mirroring ---urgent help required ********

[Trng]

Dear Gurus,

my customer is having HP Storage box and it is connected to many hpux boxes

Storage got ful and customer has purchased Netapp storgae .as a HPUX Sysadmin i have lot

of task ahead.

1-mirrorus is reqd for mirroring vgs/lvs in hpux ?

2-without mirrorux can we mirror the root lvols in hpux (lvextend –m 1 /dev/vg00/lvol11 /dev/dsk/c0t0d0)

3-many luns are assigned from hp storage and craeted a filesystem.
is it possible to mirror this filesystem to the new storage (assign luns from netapp and create logical volume )--from os level canw e do it ? any software reqd ?

4-is it possible to mirror a VG to newly added vg(netapp)..any software required for this ?


regards
trng

[Analyst]

Hi Trng,

1. mirroring requires mirror-UX software.

2. You can create a new filesystem and copy the entire thing with normal coying principle.

3. There is one concept called DRD with that we can create boot disk from storage.

4.From storage you should have RAID concept please confirm that.

Thanks,
Analyst.

[ASIFKHAN · Accepted solution]

Hi,

First thing you did not specify the name of the HP storage Box and also the model number of host connected to Storage .Is it SAN storage or NAS Storage.

Answer to possiblility to mirror rootvg without MirrorDisk Software at OS level is no,So u should have Mirrordisk to mirror LV's but There are some latest hardware server(rx2660) of HP has inbuilt RAID SCSI controller card that is helpful in mirroring it is also called Hardware mirroring.

yes it is possible to mirror the filesystem but again condition is there that the host on which this filesystem exists should be connected to new storage and if u assifn new LUN it should be able to see it in ioscan ouput and after that you can extend particular VG where your filesystem existing but remeber that in next stpe again u should have installed MirrorDisk/UX software to mirror your LVol over filesystem existing so that u can run "lvextend -m 1 LVnameoffilesystem pvdevice file name"

As far as i know that we can mirror only LV's at OS level not VG's .

Regards:
Asif khan

[Steven E. Protter]

Shalom,

1. No mirroring is not required. It can be used to replicate data.
2. Without mirror/ux you can only "mirror" using a dd command dd if=/dev/dsk/c0t0d0 of=/dev/dsk/
3 The issue is getting the data onto the netap. A simple cp -pr can do it with a single system that has access to both systems. No additional software required.

4 No software required.

SEP

[Matti_Kurkela]

I understand you're doing a storage migration from HP storage to Netapp, am I right?

1.) Yes, for the OS-level mirroring, MirrorDisk/UX is required.

2.) Only if your server has a hardware RAID controller. Some sysadmins actually prefer MirrorDisk/UX for vg00 mirroring in all servers - it is the "standard way to do things".

3.) With MirrorDisk/UX, you can mirror the filesystems to the new storage, and then delete the mirror copy from the old storage. This is a good way to migrate to a new storage system without service interruptions.

If you don't have MirrorDisk, you can still do it using the HP-UX standard command "pvmove".
The general procedure is:
- create a new LUN in new storage
- add the new LUN to the old VG
- use pvmove to move the contents of one old LUN to the new LUN
- drop the old, now-empty LUN from the VG
- repeat until all data is moved

This does not require a service interruption either.

Note that both procedures will cause a huge disk I/O when the data is mirrored/moved to the new storage system, so it's not a good idea to do this at the time of peak load.

4.) HP-UX does not have a concept of "mirroring VG to another VG": the concept is "mirroring the data of a LV to two or more PVs".

Of course, if you can take a service interruption, you can mount the LVs of the new VG to a temporary location and then manually copy all the data. The standard, portable way to copy an entire directory hierarchy and preserve all ownerships and file permissions is to use tar as root:

cd /source
tar cf - . | (cd /destination; tar xvf -)

MK

[Trng]

Hi All,

i am clear about os part and mirrorux.now my case is


my HP12000 storage box is connected to serverA and have filesytem called lvol1 (size 200GB,7 luns)..now i want to migrate this to netapp storage without any dataloss.

if netapp guy is assigned 200GB(single/multiple luns) to the same server.can we miror the lvol1 to the newly assined 200GB from netapp??? and remove the HP 200GB from this server ?

any other method to migrate the data ?


regards
trng

[Analyst]

Hi,

Your Argument is valid, but for that storage side we have concept called snapshot in EMC.
which it takes a copy of whole lun or Disk group.

you have check the same is possible from HP/Netapp.

otherwise its not mirroring , just copying the data from one filesystem to other filesystem.

choose the option which is applicable in your case.

Thanks,
Analyst.

( If the infromation is useful, kindly assign points)

[Matti_Kurkela]

> if netapp guy is assigned 200GB(single/multiple luns) to the same server.can we miror the lvol1 to the newly assined 200GB from netapp??? and remove the HP 200GB from this server ?

Maybe; it depends on your VG parameters (check the vgdisplay output).

Usually the combination of "Max PE per PV" and "PE size" values limits the size of the LUNs you can add to the VG, and the "Max PV" value limits the total number of LUNs in the VG. If these parameters allow you to add new capacity to your VG, then you can use pvmove or mirroring:

- if you can add at least as much space in new LUNs (from the new storage) as your largest current LV, you can use mirroring

- if you can add at least one new PV(=LUN) to the VG, you can use pvmove

- if your VG's Cur PV = Max PV, then you must create a new VG (with much larger parameters, allowing for future growth) and copy the data manually. No data will be lost if this is done correctly, but in most cases this requires applications to be shut down for the copy & rearrangement operations.

With HP-UX 11.31 and 11.23 with latest patches, there is one more possibility: you can use the "vgmodify" command to enlarge some of your VG parameters, enabling you to use mirroring or pvmove even if your VG is currently "full".

MK

[ASIFKHAN]

Hi ,

I do agree with Mutti Over the point that:

- if your VG's Cur PV = Max PV, then you must create a new VG (with much larger parameters, allowing for future growth) and copy the data manually. No data will be lost if this is done correctly, but in most cases this requires applications to be shut down for the copy & rearrangement operations.

But i would like to add something in it as i confirmed from my senior that in practical situation you should create another VG and add newly created LUN or LUNS of Netapp using vgcreate and then create the same number of lvols and mount points.
Then take the backup of the filesystem over the tape or disk whichever is preferrable that you want to migrate and then restore this filesystems over the newly created mount points.

It is the safest way of Data Transfer to avoid data loss but do remember that application must be shutdown while doing backup as well as restore.

--> pvmove has biggest disadvantage that if intrrupted in between data transfer then it will corrupt whole data.

--->dd command copy data bit by bit so untill & unless mechanism of this command is not clear then do not use it.

Hoping it will help you.

Thanks
Asif Khan

[Trng]

thanks gurus ..let me to do some research as per your guidance ..