[CentOS] raid 5 install

Blake Hudson
Fri, 28 Jun 2019 14:46:33 -0000

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.