[CentOS] raid 5 install

Leon Fauster
Fri, 28 Jun 2019 17:55:00 -0000

Am 28.06.2019 um 16:46 schrieb 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.
>


We have good experiences with MD RAID (Linux software RAID) - for having data
redundancy at low cost. For availability we use clustering (different hardware
level) ...

--
LF