[CentOS] RAID questions

[John R Pierce]

On 2/14/2017 4:48 PM, tdukes at palmettoshopper.com wrote:
> 1- Better to go with a hardware RAID (mainboardsupported) or software?

I would only use hardware raid if its a card with battery (or 
supercap+flash) backed writeback cache, such as a megaraid, areca, etc.  
otherwise I would use mdraid mirroring.


> 2 - Can an existing drive with data on it be used as aRAID drive without
> losing current data?

software mdraid will let you add a mirror to an existing disk.    or if 
its using LVM, you can mirror in LVM now.

> 3 - Can additional drive(s) be added later with a changein RAID level
> without current data loss?

Only some systems support that sort of restriping, and its a dangerous 
activity (if the power fails or system crashes midway through the 
restriping operation, its probably not restartable, you quite likely 
will lose the whole volume)...    with LVM mirroring, you can add more 
pairs of drives as additional mirrors to the volume group.


-- 
john r pierce, recycling bits in santa cruz