Using Disks when the RAID volume is degraded
Hi, I'm new to softRAID and I have a few questions that I don't think are made clear from the information I can find.
1. Is it possible to continue to use (ie read/write data from and to) an individual disk within a raid volume when the other disk is temporarily removed from the system?
2. If so, if the drive that wasn't in use when the first drive was altered comes back online, are the two drives automatically synched ie. Is a second copy of the new files made to the previously offline drive?
3. If so, is this done automatically or do I have to initiate the process in some way?
Thanks in advance for your help. :)
You cannot write to "individual disks", a RAID volumes shares data across all members. When a disk is missing, that disk is not written to, and becomes out of sync.
If the second drive is connected, it will rebuild into the array, yes. this is mostly automatic.
Not sure why you want to remove an individual disk, unless this is a Mirror and you are storing the disk off line?
Hi. Thanks for the reply.
No no... I don't WANT to write to one disk only. This is me trying to work out what happens if it were to accidentally happen. For example, ideally, both drives will always be on and booted and functioning properly... however... stuff happens. Plugs can get knocked out, drives can have random accessibility issues (eg sata bridges can freeze) etc. etc. I just wanted to know what would happen if I didn't notice to begin with (which, let's face it, I probably won't, even if a warning flashes up) and I continue to write files to my RAID drive.
I have to assume a RAID 1, mirror, as RAID 5, disks are in enclosures, so that would not happen.
In a Mirror, one disk is Primary, the rest are secondary disks.
If the Secondary is missing at startup, it will "rebuild" when it is connected
If the Primary is missing, then there is a problem. The Secondary has to be mounted, which "splits" the mirror, so you need to delete a volume, then "add" it back to the mirror. We have a mechanism to rebuild instead in some cases, however, so users do not see this as often. But then the Primary will have switched to the other disk, perhaps without you knowing it.
We also have a Mirror "timeout", which you can set in preferences, which is how long SoftRAID waits before mounting an incomplete volume. (and potentially splitting a mirror). Default is 15 seconds, but you can make it up to 2 minutes. the downside of setting it for two minutes is your volume will not mount until the second disks shows up, or 2 minutes pass by.