PERC H700 Online Capacity Expansion or RAID Level Migration

Vaibhav_Kumar at Dell.com Vaibhav_Kumar at Dell.com
Sun Mar 13 04:30:32 CDT 2011


Thanks Blake,

I will take up this with Doc team.

From BIOS (Ctrl + R), you can only do “Expand VD size” i.e. OCE

Regards
-Vaibhav

From: Blake Hudson [mailto:blake at ispn.net]
Sent: Saturday, March 12, 2011 4:00 AM
To: Kumar, Vaibhav
Cc: linux-poweredge-Lists
Subject: Re: PERC H700 Online Capacity Expansion or RAID Level Migration

Thanks again Vaibhav,

The Dell documentation <http://support.dell.com/support/edocs/storage/storlink/h700h800/en/ug/html/chapterb.htm#wp1070638> states the following:

Online Capacity Expansion (OCE) can be done in two ways. If there is a single virtual disk in a disk group and free space is available, the virtual disk's capacity can be expanded within that free space. If a virtual disk is created and it does not use the maximum size of the disk group, free space is available. Free space is also available when a disk group's physical disks are replaced by larger disks using the Replace Member feature. A virtual disk's capacity can also be expanded by performing an OCE operation to add more physical disks.

Unfortunately, as you have demonstrated, this is actually considered a reconfiguration (RLM) of the VD by LSI's tools. This confusion seems to be caused by the combinging of these two (similar) functions into a single section of the Dell manual - note that OCE is discussed under the "Reconfiguring Virtual Disks" section of the document.

I was able to successfully reconfigure the VD from a 3 drive RAID5 set to a 4 drive RAID5 set using the following command:
# /opt/MegaRAID/MegaCli/MegaCli64 -LDRecon start r5 [Add PhysDrv[32:3]] L0 -a0
Start Reconstruction of Virtual Drive Success.

And could check the status using:
# /opt/MegaRAID/MegaCli/MegaCli64 -LDRecon ShowProg L0 -a0
Reconstruction on VD #0 (target id #0) Completed 76% in 200 Minutes.


Four hours later I've gone from from:

Virtual Drive: 0 (Target Id: 0)
Name                :
RAID Level          : Primary-5, Secondary-0, RAID Level Qualifier-3
Size                : 837.25 GB
State               : Optimal
Strip Size          : 64 KB
Number Of Drives    : 3
To:

Virtual Drive: 0 (Target Id: 0)
Name                :
RAID Level          : Primary-5, Secondary-0, RAID Level Qualifier-3
Size                : 1.225 TB
State               : Optimal
Strip Size          : 64 KB
Number Of Drives    : 4


It's not the fastest, but it works.

May I ask why there is no option in the Dell BIOS to reconfigure a virtual drive? or did I miss it?

Thanks for the help,
--Blake



-------- Original Message  --------
Subject: Re: PERC H700 Online Capacity Expansion or RAID Level Migration
From: <Vaibhav_Kumar at Dell.com><mailto:Vaibhav_Kumar at Dell.com>
To: blake at ispn.net<mailto:blake at ispn.net>
Cc: linux-poweredge at lists.us.dell.com<mailto:linux-poweredge at lists.us.dell.com>
Date: Friday, March 11, 2011 10:20:13 AM


I could find the below command for Reconfigure ("RAID level Migration")



MegaCli -LDRecon {-Start -rX [{-Add | -Rmv} -Physdrv[E0:S0,...>}|-ShowProg|-ProgDsply -Lx -aN



Try this.



Regards

-Vaibhav





-----Original Message-----

From: Blake Hudson [mailto:blake at ispn.net]

Sent: Friday, March 11, 2011 9:14 PM

To: Kumar, Vaibhav

Cc: linux-poweredge-Lists

Subject: Re: PERC H700 Online Capacity Expansion or RAID Level Migration



Thanks Vaibhav, that explains why "Expand VD" was not available. So, my

next question is how do I "go for RAID level migration"?



The Dell manual does state that I should be able to migrate from a RAID5

to a RAID0. But does not state how. I do not see an option for migration

in the BIOS nor the MegaCLI tool from LSI. I would appreciate it if you

could point me in the right direction.



Thanks,

--Blake





-------- Original Message  --------

Subject: Re: PERC H700 Online Capacity Expansion or RAID Level Migration

From: <Vaibhav_Kumar at Dell.com><mailto:Vaibhav_Kumar at Dell.com>

To: blake at ispn.net<mailto:blake at ispn.net>, linux-poweredge at lists.us.dell.com<mailto:linux-poweredge at lists.us.dell.com>

Date: Friday, March 11, 2011 9:00:47 AM

"Online Capacity Expansion" helps to increase the size of a Partial VD within the same disk group _only_.



Ex - You create a 15 GB RAID-5 VD using 3 disks each of 10GB. Here, you can do "Online Capacity Expansion" to 5 GB more.

     But, If You create a 20 GB RAID-5 VD using 3 disks each of 10GB, then "Online Capacity Expansion" is _not_ possible as all disk space is already utilized.







Whereas "RAID level migration" helps to migrate to another RAID level. Here, size may or may not increase.



Ex -  You create a 20 GB RAID-5 VD using 3 disks each of 10GB. Here, if you add 1 more disk of 10GB size and migrate to RAID-6, you will get a 20GB RAID-6 VD. Here if you see, there is no size increase.

      Similarly, You create a 20 GB RAID-5 VD using 3 disks each of 10GB. Here, without adding disk, you can migrate to 30 GB RAID-0 VD. Here if you see, there is a size increase.





So, If you are seeing "Expand VD" as grayed out, check out for below

- There is free space remaining on your VD.

- There is no BGI or normal Initialization is running on.



And if you want to move from RAID-5 to RAID-6, "Expand VD" is not the way. You need to go for "RAID level migration"



Regards

-Vaibhav





-----Original Message-----

From: linux-poweredge-bounces-Lists On Behalf Of Blake Hudson

Sent: Thursday, March 10, 2011 10:49 PM

To: linux-poweredge-Lists

Subject: PERC H700 Online Capacity Expansion or RAID Level Migration



In the documentation for the PERC H700/800, it lists both Online

Capacity Expansion and Raid Level Migration as features available to the

H700. However, I have been testing with an H700 and 5 SAS drives and

have yet to be able to make this work.



Initially, I setup a 4 drive RAID5 (intending to expand to a 5 drive

RAID5). Both the 4 drives in the RAID set and a single, unconfigured

drive are installed in the chassis. However, in the PERC BIOS, the

option for 'Expand VD' is disabled and grayed out.



After reading the manual, I saw that RAID5 migration to a RAID0 or RAID6

should specifically be available - an additional drive is required for

the RAID6 migration though. Thinking that I may need an additional spare

drive, I reconfigured the RAID5 array using 3 drives, leaving 2 spare.

Unforutnately, the 'Expand VD' option is still disabled in the PERC BIOS.



I attempted to use the MegaCLI tool to expand the VD and see the

following message"

[root at server ~]# /opt/MegaRAID/MegaCli/MegaCli64 -getLdExpansionInfo

-Lall -aALL





Virtual Disk: 0 (Target Id: 0)

Expansion                                                     : Not

Possible



Exit Code: 0x00

[root at server ~]#



Both the PERC and LSI manuals are a little thin when it comes to either

of these topics. Has anyone actually performed either of these functions

on a PERC? If so, how did you do it?



Thanks,

--Blake





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