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Topic starter
Using SoftRaid Lite how easy is it to rebuild a failed Mirror Raid (raid 1) ?
I was using two G Tech 8Tb Thunderbolt Raid drives ( each unit is a Raid 0 for speed ) , these were Raided in MAC Disc Utility into a Raid 1 for redundancy, so effectively creating a Raid 0 + 1 for combined speed and redundancy.
One of the G Tech units failed (although the MAC Disc utility doesn't tell you! ) and it seems there is no easy way to rebuild the Raid using the disc utility. I effectively have to copy everything off the good drive onto another drive, then rebuild the Raid pair from scratch and copy the data back onto it.
Would this be the same scenario if I was using Softraid Lite or is there a utility in the system to rebuild a failed raid pair? I'm going to switch to Softraid anyway as it will tell me if my Raid has failed (or maybe even before it does) but I'd like to know the options when it does fail or appears as if it might fail.
Thanks
gavin.
Posted : 27/12/2015 7:44 pm
SoftRAID is much easier, and often automatic. There are different failure modes:
A) A disk can drop out for a period of time (or be removed as an off site archive/copy)
B) A disk can temporarily fail, generating disk errors
C) A disk can permanently fail.
If the secondary disk is the afflicted disk, then A and B are similar. SoftRAID will notify you via dialog box that there is a missing disk. (or by email if SoftRAID "retail".) When the secondary disk is connected again, it will automatically rebuild.
Note: If the volume has been rebuilt or validated previously, then the rebuild will be extremely fast, as SoftRAID will know what parts of the disk has changed and only rebuild those parts.
If "C" occurs, where a disk fails permanently, you simply need to connect a new disk (we recommend pre-certifying the disk), initialize it with SoftRAID, then use "Add Secondary Disk". You may also need to reset the secondary disk counter by "remove missing secondary disks". SoftRAID supports up to 16 disks in a mirror volume.
If the primary disk fails or is missing, then you have a failover event.
When a primary disk is not available, SoftRAID waits for a short while, then selects a secondary disk and makes it a Primary of a new volume. When the original primary shows up, hte user must determine which should be the new primary "manually". Then you just delete the prior volume and "add secondary disk" again.
One difference with Apple's RAID and SoftRAID is SoftRAID uses the Primary/Secondary method to ensure that you always have a "gold master" reference disk that all secondary are synchronized to. Apple's RAID does not use this method, so it is easily possible, with removable disks, to end up with disks that have different data on them that are not identified as being out of sync.
Posted : 27/12/2015 8:06 pm
Topic starter
SoftRAID is much easier, and often automatic. There are different failure modes:
A) A disk can drop out for a period of time (or be removed as an off site archive/copy)
B) A disk can temporarily fail, generating disk errors
C) A disk can permanently fail.If the secondary disk is the afflicted disk, then A and B are similar. SoftRAID will notify you via dialog box that there is a missing disk. (or by email if SoftRAID "retail".) When the secondary disk is connected again, it will automatically rebuild.
Note: If the volume has been rebuilt or validated previously, then the rebuild will be extremely fast, as SoftRAID will know what parts of the disk has changed and only rebuild those parts.
If "C" occurs, where a disk fails permanently, you simply need to connect a new disk (we recommend pre-certifying the disk), initialize it with SoftRAID, then use "Add Secondary Disk". You may also need to reset the secondary disk counter by "remove missing secondary disks". SoftRAID supports up to 16 disks in a mirror volume.
If the primary disk fails or is missing, then you have a failover event.
When a primary disk is not available, SoftRAID waits for a short while, then selects a secondary disk and makes it a Primary of a new volume. When the original primary shows up, hte user must determine which should be the new primary "manually". Then you just delete the prior volume and "add secondary disk" again.One difference with Apple's RAID and SoftRAID is SoftRAID uses the Primary/Secondary method to ensure that you always have a "gold master" reference disk that all secondary are synchronized to. Apple's RAID does not use this method, so it is easily possible, with removable disks, to end up with disks that have different data on them that are not identified as being out of sync.
Posted : 28/12/2015 4:03 am
Topic starter
Thanks for that. Sounds much better than the MAC Utility which gave me no option to repair the Raid.
Gavin.
Posted : 28/12/2015 4:04 am
