How can I tell which raid level I'm using??

[berrick]

Originally setup using freenas 8.2 as a raid 5? due to lack of memory.

I recently upgraded to 9.1.1.

Due to some strange goings on after the upgrade I paid a little more attention to the boot messages but couldn't see any mention of raid 5 only raid 3. If I loose a disk the system still boots but I can't access the data on the Volume I have created and I should if the volume is raid 5.

Can any one offer some insight?

Many thanks

 

[cyberjock]

Not without you posting more information.

What hardware do you have? Can you provide the output of the command dmesg shortly after bootup? You can direct the output to a file with dmesg > /mnt/(poolname)/filename. It is quite long, so a screenshot won't be sufficient.

When you say RAID5/RAID3 are you talking UFS or hardware RAID? I know you aren't talking about ZFS because it doesn't ever say RAID5, and there is no RAID3 equivalent.

 

[berrick]

Hi cyberjock,

• Yes the volume is UFS
• No there is not hardware raid controller

I cant reboot the NAS just at the present so I will post the output later today.
Interesting read on Raid 5. I hadn't considered URE. Fortunately I do periodically backup to tape

 

[cyberjock]

You should be okay with posting the dmesg without a reboot recently as dmesg only shows so many lines of log since bootup. If its been weeks or months you might not get everything. I'd say post what you get and see if a reboot is necessary.

Still need the hardware specs as I requested before though. ;)

 

[berrick]

Here at last is the information you requested.

• CPU AMD Athalon x64 Dual core 5200+ 2.6Ghz
• Mem 1Gig DDR2

dmesg output http s://dl.dropboxusercontent.com/u/55473978/BerrickFreeNAS911.txt

 

[berrick]

Hi cyberjock,

I can see your the busiest on the forum but did you get chance to look at the info you asked for which I posted above?

 

[paleoN]

Originally setup using freenas 8.2 as a raid 5? due to lack of memory.

FreeNAS 8.2 uses UFS2 based volumes, including gmirror, gstripe, and graid3 via the GUI.

 

[cyberjock]

Sorry, I don't have any recommendations at this point. Normally its recommended you have at least 2GB of RAM for UFS with FreeNAS. I don't use UFS so I can't provide much more advice in that regard. You might want to consult the FreeNAS manual. I'll see if I can make a UFS raid later to see how you determine what you have. But if removing one disk makes your data unavailable, my guess is you have a stripe.

Edit: Answered the wrong thread with the wrong question. Answer above changed.

 

[berrick]

My apologies for the delay this had to take a back seat.

I understand the recommendation about memory. This nas box is your typical "I'll give it a try with what I have and see" and just worked and never got upgraded.

I'm a little confused about this though

if removing one disk makes your data unavailable, my guess is you have a stripe

My understanding was that raid 3, 4 and 5 stripped data across all disk in the array. Raid 3 and 4 use dedicated disk for parity whereas raid 5 distributed parity evenly across all disks. Consequently as we have parity one disk can fail, be replaced and integrity of the raid and data be rebuilt.

I use mirrored drives and Raid 5 mostly and one drive failure doesn't stop data being used so don't understand why loosing one disk in the FreeNas box causes me not to see data? I still have parity and all other data.

tyia

 

[jgreco]

the results of dmesg at boot time are cached in /var/run/dmesg.boot

 

[berrick]

Okay, I'm really confused now.....

• Freenas states minimum number of disks for raid 5 is 3.
• I have three disk which I thought where configured as raid 5
• dmseg only mentioned Raid3

Out of curiosity I added a cheap PCI via chipset sata controller and added an additional disk. Now dmseg mentions raid3 and raid5.
To me this says that my disks aren't running in raid 5? Would that be the consensus of the more experienced?

 

[Dusan]

What you have is UFS RAID3 (www.freebsd.org/cgi/man.cgi?query=graid3).
FreeNAS doesn't do RAID5 at all: http://doc.freenas.org/index.php/Volumes#Auto_Importing_Volumes

UFS RAID5 is not supported as it is an unmaintained summer of code project which was never integrated into FreeBSD.

You can verify this by running: graid3 status

 

[berrick]

Phew, thanks for the links Dusan! I was beginning to think I was loosing it as I was reading the following from the manual. I took this to mean Raid 5 was supported. The fact that I'm now seeing graid5 mentioned just gave more weight to this thinking.

Maybe it should be made clear at this point in the manual which raid versions are supported? for us less informed.
RAID Overview

Data redundancy and speed are important considerations for any network attached storage system. Most NAS systems use multiple disks to store data, meaning you should decide which type of RAID to use before installing FreeNAS®. This section provides an overview of RAID types to assist you in deciding which type best suits your requirements.
RAID 5: requires a minimum of three disks and can tolerate the loss of one disk without losing data. Disk reads are fast but write speed can be reduced by as much as 50%. If a disk fails, it is marked as degraded but the system will continue to operate until the drive is replaced and the RAID is rebuilt. However, should another disk fail before the RAID is rebuilt, all data will be lost.

 

[Dusan]

Yes, I agree the manual could be clearer. That section only explains various RAID levels, but does not make it clear what is actually supported. It also does not mention RAID3 at all. I already did this quick edit to remove a sentence that was implying RAID5 was supported: http://doc.freenas.org/index.php?title=Hardware_Recommendations&curid=6&diff=9858&oldid=9850