Disk replacement RAID 5

Question

I have a power edge T420 that has a RAID50 setup on it. One disk failed and I am going to replace it. I learned that RAID exists on Wednesday so before I go ahead I wanted to ask someone to double check if what I plan will work. Thanks!

I've installed the command line tool and here are its outputs:

root@server:/opt/MegaRAID/perccli# ./perccli64 /c0/eall/sall show
CLI Version = 007.1910.0000.0000 Oct 08, 2021
Operating system = Linux 5.10.0-19-amd64
Controller = 0
Status = Success
Description = Show Drive Information Succeeded.


Drive Information :
=================

-----------------------------------------------------------------------------------
EID:Slt DID State  DG       Size Intf Med SED PI SeSz Model                Sp Type
-----------------------------------------------------------------------------------
32:0      0 UGood  -  111.250 GB SATA SSD N   N  512B INTEL SSDSC2BB120G6R U  -
32:1      1 UGood  -  111.250 GB SATA SSD N   N  512B INTEL SSDSC2BB120G6R U  -
32:2      2 Onln   0    3.637 TB SAS  HDD N   N  512B ST4000NM0025         U  -
32:3      3 Onln   0    3.637 TB SAS  HDD N   N  512B ST4000NM0025         U  -
32:4      4 Onln   0    3.637 TB SAS  HDD N   N  512B ST4000NM0025         U  -
32:5      5 Onln   0    3.637 TB SAS  HDD N   N  512B ST4000NM0025         U  -
32:6      6 Onln   0    3.637 TB SAS  HDD N   N  512B ST4000NM0025         U  -
32:7      7 Failed 0    3.637 TB SAS  HDD N   N  512B ST4000NM0025         U  -
-----------------------------------------------------------------------------------

EID=Enclosure Device ID|Slt=Slot No|DID=Device ID|DG=DriveGroup
DHS=Dedicated Hot Spare|UGood=Unconfigured Good|GHS=Global Hotspare
UBad=Unconfigured Bad|Sntze=Sanitize|Onln=Online|Offln=Offline|Intf=Interface
Med=Media Type|SED=Self Encryptive Drive|PI=Protection Info
SeSz=Sector Size|Sp=Spun|U=Up|D=Down|T=Transition|F=Foreign
UGUnsp=UGood Unsupported|UGShld=UGood shielded|HSPShld=Hotspare shielded
CFShld=Configured shielded|Cpybck=CopyBack|CBShld=Copyback Shielded
UBUnsp=UBad Unsupported|Rbld=Rebuild

root@server:/opt/MegaRAID/perccli# ./perccli64 /c0/dall show
CLI Version = 007.1910.0000.0000 Oct 08, 2021
Operating system = Linux 5.10.0-19-amd64
Controller = 0
Status = Success
Description = Show Drive Group Succeeded


TOPOLOGY :
========

------------------------------------------------------------------------------
DG Arr Row EID:Slot DID Type   State  BT      Size PDC  PI SED DS3  FSpace TR
------------------------------------------------------------------------------
 0 -   -   -        -   RAID50 Dgrd   N  14.552 TB dsbl N  N   dflt N      N
 0 0   -   -        -   RAID5  Dgrd   N   7.276 TB dsbl N  N   dflt N      N
 0 0   0   32:2     2   DRIVE  Onln   N   3.637 TB dsbl N  N   dflt -      N
 0 0   1   32:3     3   DRIVE  Onln   N   3.637 TB dsbl N  N   dflt -      N
 0 0   2   32:4     4   DRIVE  Onln   N   3.637 TB dsbl N  N   dflt -      N
 0 1   -   -        -   RAID5  Dgrd   N   7.276 TB dsbl N  N   dflt N      N
 0 1   0   32:5     5   DRIVE  Onln   N   3.637 TB dsbl N  N   dflt -      N
 0 1   1   32:6     6   DRIVE  Onln   N   3.637 TB dsbl N  N   dflt -      N
 0 1   2   32:7     7   DRIVE  Failed N   3.637 TB dsbl N  N   dflt -      N
------------------------------------------------------------------------------

DG=Disk Group Index|Arr=Array Index|Row=Row Index|EID=Enclosure Device ID
DID=Device ID|Type=Drive Type|Onln=Online|Rbld=Rebuild|Optl=Optimal|Dgrd=Degraded
Pdgd=Partially degraded|Offln=Offline|BT=Background Task Active
PDC=PD Cache|PI=Protection Info|SED=Self Encrypting Drive|Frgn=Foreign
DS3=Dimmer Switch 3|dflt=Default|Msng=Missing|FSpace=Free Space Present
TR=Transport Ready

My plan is to do as follows:

1. I will switch the disk off

perccli /c0/e32/s7 set offline
perccli /c0/e32/s7 set missing
perccli /c0/e32/s7 set spindown

2. I will swap the drive sitting in the tower

3. I will bring it back with

perccli /c0/e32/s7 set spinup
# perccli /c0/e32/s7 set online # idk in what order this one should go
perccli /c0/e32/s7 insert dg=0 array=1 row=2
perccli /c0/e32/s7 start rebuild
perccli /c0/e32/s7 show rebuild

That's it.

So as you can see I have pretty much just collected a bunch of commands from the manual and I have lined them up in what I hope makes sense, but to be honest I have no idea what am I doing. So if someone can help me out with it that would be much appreciated!

Dell-Dheeraj · Accepted Answer

Hi @BabyItsColdOutside

If the drive status is already failed, there is no need to mark the drive as offline.

Offline- This means that the disk is in an offline state and is not available for any activity/ data transfers.

Missing- This state refers to that the disk was recently available on the system but can no longer be located or identified. The missing disk may be corrupted, powered down, or disconnected.

Spun down- In this state, the disk will go into standby mode after a certain period of inactivity. Due to this, the power usage will be reduced and the disk life will be extended, but there will be latency before the disk can be accessed again for critical activities.

DELL-Young E · Answer

Hi, this may help. https://dell.to/3uYQhyK

BabyItsColdOutside · Answer

Thank your for the reference. It is an interesting case that describes similar problem, I learned a lot from that example.

The one difference in my case is that instead of 'predicted fail', the drive I work with is already marked as 'failed'. Does it still make sense to set it 'offline' before replacement?

I read the perc-cli manual and it does a great job in explaining how to set the disk in various states. Unfortunately, the manual does not explain what are these states. Would you be able to help me tell the difference between the 'offline', 'missing', and 'spun down' states of a disk?

If you could point me to some reference on where I can learn about it, I would also greatly appreciate it.

Thank you!

BabyItsColdOutside · Answer

Thank you for this quick answer. It works great, although I still hesitates a bit before pressing the disk eject button. Here is what I did, as a reference:

I didn't do anything with any software before removing the drive. I simply took the drive out of the server. I have replaced it with a new drive and put it back into the server. For about 30 sec not much happened. After that the disk changed its status to 'rebuild'. Literary no need to do anything other than replacing the failed physical drive.

Thanks again for the help!

PowerEdge HDD/SCSI/RAID

Disk replacement RAID 5

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