RE: [CentOS] Recommendations for a “real RAID" 1 card on Centos box

[Therese Trudeau]

>> I'm just really looking for a RAID card that will do RAID 1, with four drive capacity, i.e.,
>> a master drive with the OS and applications installed and mirrored, and a slave drive for data and
>> photos, graphic design, video, etc also mirrored.  What would battery built into a RAID card 
>> do for me? 
> 
> the whole point of a BBU is that you can turn on write back caching -
> and get a fair win in write performance on regular tasks.

Pardon my ignorance, what is write back caching and BBU?
 
> Also, make sure whatever raid hardware you decide to invest in supports
> multiple raid sets ( thats what you seem to want - and not all raid
> cards do that ) - both 3ware and Areca do support this.

Do you mean by multiple raid sets a raid card that can do either RAID 0, RAID 1, RAID 5 etc?

> Are you considering using this as a backup system and not doing any off
> machine backups ? if so, consider the possibility of actually loosing
> the raid card itself : Ideally you want the raid metadata sitting on the
> disks rather than the raid card, so you can replace the card and be back
> in action. Again, not all cards support this out of the box.

Yes, this is just to back up my hard drives on my desktop machine, no remote
backups.  Do both the 3ware and the Areca store meta data on disk?
 
>> So you reccomend Areca, good thanks I'll check them out too.  How are they for RAID 1?
> 
> To be honest, its been a very long time since I used a raid-1 setup, and
> I am not sure if I'd bother with it now. If you have 4 drives, might as
> well raid-5 them. You still get the ability to loose 1 drive at a time,
> and have a hot-spare : while ending up with the same storage capacity.

Again pardon my ignorance, what is a hot spare?  A blank drive connected
in the RAID 5 setup that can be written to in case one of the other 3 drives fail?

> btw, if you have 4 drives, make sure they are as similar in
> specifications as possible - however, try and get different batch
> numbers / production runs. Drives that were made in the same batch, have
> been stored and stock under the exact same conditions, shipped out
> together, used and put into production together - have a very very high
> probability of also failing together :D

OK Will do that for sure when I set this up. 


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