New Build - Growing/Upgrading RAID

Carnajo · 31. Oktober 2012

Hi,

I'm busy planning a new build having recently purchased an HP Microserver N40L.

I'd like to start with two 3TB drives and over time add a third and fourth drive to eventually have RAID 5 (9TB storage, 3TB parity drive). I believe it is possible to grow a RAID array. What is the best way to start the RAID array? Possibly 2 Drives as RAID 0/1 and then grow it to RAID 5 when I get a third drive? I believe this can be quite tricky, is it doable or should I fork out now for 3 drives RAID 5 and then grow it to 4 drives?

Thank you for any assistance.

ryecoaaron · 31. Oktober 2012

Raid 0 would offer you no protection. Raid 1 would only give you 3 tb of space. You could manually setup raid 5 without the parity drive if you weren't concerned about data loss (same as raid 0) until you get the third drive. I would just save all the hassle and get the third drive now.

Carnajo · 1. November 2012

Thanks, I'll go for 3x3TB initially and get a fourth one as I need it.

SerErris · 3. November 2012

And for avoidance of doubt; You cannot upgrade a Raid1 to a Raid5. If you created a Raid1 you are stuck with a Raid 1.

Carnajo · 5. November 2012

Thanks very much, definitely a deciding factor.

mebkopcznski · 7. November 2012

I intend to do same, but I do have a question?
What would be the best filesystem to use with it? EXT3,EXT4, XFS or JFS?
After installing three drivers and using RAID5. It is possible to grow the RAID adding a new disk and after that, it is possible to grow the filesystem?
Thanks in advance.

ryecoaaron · 7. November 2012

The best filesystem is a personal preference and depends on what you are using it for. Yes, you can grow the filesystem. Just use the following commands while unmounted.

e2fsck -f /dev/mdX
resize2fs /dev/mdX

fpabernard · 19. November 2012

I would personally use XFS.

At work, my organization had deployed many desktops under Linux Ubuntu, using EXT3, and we had to reinstall everything with XFS ... because of data loss problems by some users ...

I use Openmediavault with XFS on RAID5 / LVM, it's perfect.

fpabernard · 20. November 2012

Upgrowing a RAID on which a logical volume is installed with a XFS file system on it, it seems that everything can be done using WebGUI ... except resizing the physical volume, what requires a pvresize command.

I understand that the procedure is, after the new volume is physically added to the system :

In Web GUI :

System->Storage->RAID->Grow

RAID is resyncing and recovering

In a shell

Code

pvresize /dev/md<XXX>

In Web GUI :

System->Storage->LVM->Logical Volume->Extend

System->File Systems->Resize

It's a little too bad to have to return to shell just for one command, isn't it ?

fpabernard · 25. November 2012

Zitat von "SerErris"

And for avoidance of doubt; You cannot upgrade a Raid1 to a Raid5. If you created a Raid1 you are stuck with a Raid 1.

Hum !!!

In the documentation of mdadm, they say you can change level of RAID1 to RAID5

See my post here : http://forums.openmediavault.o…pic.php?f=11&t=1063#p3772

JDMorrison · 25. Januar 2013

Zitat von "fpabernard"

I would personally use XFS.

At work, my organization had deployed many desktops under Linux Ubuntu, using EXT3, and we had to reinstall everything with XFS ... because of data loss problems by some users ...

I use Openmediavault with XFS on RAID5 / LVM, it's perfect.

I'm in the process of setting up my own OMV server for the first time and doing research, when I cam accross this very useful thread.

I have a question though, if your drives are already in a RAID, why LVM? Do you have multiple raids and have grouped them together in one logical volume?

Tom · 25. Januar 2013

Zitat von "JDMorrison"

I'm in the process of setting up my own OMV server for the first time and doing research, when I cam accross this very useful thread.

I have a question though, if your drives are already in a RAID, why LVM? Do you have multiple raids and have grouped them together in one logical volume?

Because if you extend your RAID one day, you can easily extend the physical volume, volume group and the logical volume.

SerErris · 26. Januar 2013

Zitat von "fpabernard"

Hum !!!

In the documentation of mdadm, they say you can change level of RAID1 to RAID5

See my post here : http://forums.openmediavault.o…pic.php?f=11&t=1063#p3772

Okay, to be more specific:
You cannot upgrade Raid1 to Raid5 with the current version of OMV.

And yes, I know that this is possible with newer kernels and mdadm versions, but starting with backports in that environment is definately beyond normal users capabilities. That is the reason why I would not recommend it here.

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