Software RAID

Software RAID
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Software RAID
Software RAID
If your hardware has enough ram to use ZFS, then you should be using ZFS, and not any other form of
software or hardware RAID. Software and hardware RAID DO NOT provide the kind of robust data
protection that ZFS redundancy and checksums provide. ZFS checksums are done at the block level
and can detect and repair bitrot transparently. Software and hardware RAID DO NOT provide these
block-level protections. Software and hardware RAID will ignorantly pass corrupted data to the system
AND there is no mechanism for the system to respond with, “This data is corrupt. Please consult some
other part of the RAID.”
You can use software or hardware RAID if you want. But, you have been warned.
NAS4Free supports Software JBOD, RAID 0, 1 and 5 configurations as well as Hardware RAID. This
section describes configuring Software RAID 5. The process is virtually identical for all the others with
the exception of using geom. Vinum (unstable).
Here is the FreeBSD module name and equivalent:
JBOD: Geom concat
RAID 0: Geom stripe
RAID 1: Geom mirror
RAID 5: Geom RAID5 (Thanks to Arne for developing this non official FreeBSD module!!)
All disks must be the same size for all RAID types with the exception of JBOD and Geom RAID5 (it will
be based on the smallest disk).
Important - RAID does not equal backup. Even if you create a RAID array you must still keep another
copy of your data in a different location.
The NAS4Free team recommends configuring each of the RAID Disks as standalone Storage Disks first
to ensure they are fully functional and supported under NAS4Free. Once confirmed, remove any of the
mount points and Disks for the RAID drives to ensure a clean start. The following description assumes
that the drives have been confirmed as functional.
The High-Level process flow for configuring a simple RAID array is:
1.
2.
3.
4.
5.
6.
7.
Add Disks
Format Disks for “Software RAID”
Create the RAID array using the previously formatted for “Software RAID”
Format the newly created RAID array in UFS filesystem
Add Mount Point
Enable Services (CIFS, FTP, etc.)
For CIFS you have to create share.
To remove a RAID array, remove the mount point first and delete the RAID.
Add the Disks
Follow the Add Disk process as described above to add each of the Disks to be used in a RAID array.
In the example below, I have added 4 identically sized hard drives.
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Ensure the drives are in an ONLINE status.
You cannot use the 2nd partition of a NAS4Free boot drive as a part of a RAID array. Only whole disks
can be used to form a RAID array.
Prepare (format) the disks
Open the Disk:Format TAB, select each of the Disks in turn and ensure the File system is changed to
Software RAID, click the Format Disk button and confirm your action.
Repeat for all Disks to be used in the RAID array.
The result should be for example:
Erasing MBR and all partitions:
Creating one partition:
******* Working on device /dev/ad1 *******
Initializing partition:
Destroying old GMIRROR information:
Done!
Create the Software RAID array
Open the Disks/Software RAID page and choose your Software RAID type.
For our example, we select ‘Geom RAID5’:
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Click the
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Software RAID
icon on the right hand side to Add a new RAID 5.
Enter a RAID name for the RAID.
Click and select each of the drives to be used in this RAID array.
Drives will not appear here unless they have previously been formatted as Software RAID
Click the Add button and when prompted, click the Apply Changes button.
Creating a RAID 5 array can take a long time:
But you can use your raid during the building process! (even if it’s in ‘REBUILDING state).
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The status field will not immediately update.
Format the software RAID array
When the Status is up or rebuilding, then the RAID array must be formatted.
Open the Disk:Format menu and choose the newly created RAID array:
Leave the Type as UFS (GPT and Soft Update), click the Format Disk button and confirm.
A display similar to this should be output (example when the RAID 5 was in state ‘rebuilding’):
(You should have lot’s of more line as this example! On this example the drive was a small 200MB)
Create the mount point
Once the RAID array is formatted, all that is left is to mount the array. Open the Disk/Mount Point
page and click the
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Software RAID
From the Disk drop down, select the RAID disk. The RAID name you previously configured is visible.
Change the Partition to EFI – GPT
Enter a useful Share name and click the Add button.
The Status should display as configuring, and then click the Apply Changes button and the Status
should update to UP.
Your Geom RAID5 array is now ready for use. If you have already enabled CIFS, FTP or NFS, then the
array, with the defined Share name, will be visible across you network.
Software RAID array status
You can verify the status of your RAID array from:
Status/Disks page and select the Information Tab
Disks/Software RAID/geom used page and select the Information Tab.
A healthy RAID array will show all the State: values as UP or COMPLETE.
RAID 1 and RAID 5 arrays may take some time to synchronise completely, be patient and monitor the
status of the RAID synchronisation by continuing to refresh the Information page.
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Replacing a failed hard drive on a gmirror array
Note - Supplemental step by step instructions for removing / replacing failed drives in SoftRAID1 and
SoftRAID 5 arrays are available in FAQs:
How do I remove / replace a disk in a SoftRAID1 array ?
How do I remove / replace a disk in a SoftRAID5 array ?
In the case of a failure on one hard drive, your RAID array is in the ‘DEGRADED’ state:
Here is an example with the RAID 1 array named “mirroire” in “DEGRADED” state with a missing hard
drive:
And we can check that the disk is missing in the Disk/Management page:
We can see that in our example, the disk da1 is missing.
First Step
For replacing this disk: Stop NAS4Free and replace this disk with a new one (in the same place on the
ATA or SCSI channel). And restart NAS4Free.
After restarting NAS4Free, the Disk/Management should display it back (ONLINE if it’s the same, or
CHANGED if it’s a different disk).
The Software RAID 1 status is still ‘DEGRADED’, we must add this new disk:
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Software RAID
Second Step
Open the Disk/Software RAID/Geom mirror/Tools page and select your DEGRADED RAID array and
action “forget” (The Disk field is not used on this first action).
Third Step
Still on this Disk/Software RAID/Geom mirror/Tools page, re-select your DEGRADED RAID array, the
select the newly replaced Disk, and choose action “insert”:
You can now check your RAID status (Disk/Software RAID/Geom mirror): It should be ‘REBUILDING” or
“COMPLETE” (the time needed for rebuilding depend of your disk size).
You should check the Disk/Mount Status too, as sometimes needs a remount.
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Replacing a failed hard drive on a graid5 array
In the case of a failure on one hard drive, your RAID array is in the ‘DEGRADED’ state.
Here is an example with the RAID 5 array “bigdisk” with a missing hard drive:
And the disk is missing:
First Step
For replacing this disk: Stop NAS4Free and replace this disk with a new one (in the same place on the
ATA or SCSI channel). And restart NAS4Free.
After restarting NAS4Free, the Disk/Management should display it back (ONLINE if it’s the same, or
CHANGED if it’s a different disk).
The Software RAID 5 status is still ‘DEGRADED’, we must add this new disk:
Second Step
Open the Disk/Software RAID/Geom Raid5/Tools page and select your DEGRADED RAID array, the
replaced Disk name and action “insert”.
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Software RAID
You can now check your RAID status (Disk/Software RAID/Geom raid5): It should be ‘REBUILDING” or
“COMPLETE” (the time needed for rebuilding depends on your disk size).
You should check the Disk/Mount Status too, as sometimes needs a remount.
Software RAID configuration with geom vinum
Geom Vinum is all in one module permits you to create a software RAID 0,1 and 5 array. But, for the
moment the NAS4Free team doesn’t recommend you to use it because too many users have met with
problems using the RAID 5 option of this tool.
Complex Software RAID combinations (RAID 1+0, 5+0, etc..)
NAS4Free permits you to create advanced Software RAID combinations, for example:
RAID 1+0: Permits you to create a RAID 0 array using RAID 1 arrays
RAID 5+0: Permits you to create a RAID 0 array using RAID 5 arrays
RAID X + Y: Permits you to create a RAID Y array using RAID X arrays
The High-Level process flow for configuring a complex RAID X + Y array is:
1.
2.
3.
4.
5.
Add the Disks (4 disks minimum for a RAID 1+0, 6 disks for a RAID 5+0)
Format Disks for “Software RAID”
Create the RAID X arrays using the previously formatted for “Software RAID”
Format the newly created RAID X arrays for “Software RAID”
Create the RAID Y array using the previously RAID X arrays formatted for “Software RAID”
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6. Add Mount Point
7. Enable Services (CIFS, FTP, etc.)
From:
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Permanent link:
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Last update: 2016/02/19 10:33
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