[CentOS] raid 5 install

Fri Jun 28 14:46:33 UTC 2019
Blake Hudson <blake at ispn.net>

Nikos Gatsis - Qbit wrote on 6/27/2019 8:36 AM:
> Hello list.
> The next days we are going to install Centos 7 on a new server, with 
> 4*3Tb sata hdd as raid-5. We will use the graphical interface to 
> install and set up raid.
> Do I have to consider anything before installation, because the disks 
> are very large?
> Does the graphical use the parted to set/format the raid?

Hi Nikos, I've read the other posts in this thread and wanted to provide 
my perspective. I've used Linux RAID at various times over the past 
10-20 years with both desktop and server class hardware. I've also used 
hardware RAID controllers from 3ware, Adaptec, LSI, AMI, and others with 
IDE, SATA, SAS, and SCSI drives. The goal of RAID 1 and above is to 
increase availability. Unfortunately, I've never had Linux software RAID 
improve availability - it has only decreased availability for me. This 
has been due to a combination of hardware and software issues that are 
are generally handled well by HW RAID controllers, but are often handled 
poorly or unpredictably by desktop oriented hardware and Linux software.

Given that Linux software RAID does not achieve the goal of RAID 
(improved availability), my recommendation would be to avoid it. If you 
are looking for a backup mechanism, RAID is not it (use a backup program 
instead). If you do need high availability, my recommendation is to 
purchase an LSI based RAID controller. If you plan to use RAID 5, make 
sure the model you choose has a write cache (this could double the cost 
of the controller). Used IBM, HP, or Dell RAID controllers are available 
for a reasonable price or you can purchase a new one from Newegg or 
wherever. SAS RAID controllers will work with either SAS or SATA drives 
and you can purchase the appropriate breakout cables for connecting the 
controller to individual drives. Since you're planning on using 3TB+ 
drives that are likely 4k native sector, I'd recommend a newer model 
controller like the Dell PERC H730 (LSI MegaRAID SAS 9361-8i) for 
RAID5/6 or a PERC H330 (LSI MegaRAID SAS 9341-8i) for RAID 0/1/10.