Re: [gentoo-user] which linux RAID setup to choose?

[Caveman Al Toraboran <toraboracaveman@protonmail.com>]

On Monday, May 4, 2020 2:50 AM, hitachi303 <gentoo-user@konstantinhansen.de> wrote:

> Am 03.05.2020 um 23:46 schrieb Caveman Al Toraboran:
>
> > so, in summary:
> > /------------------------------------------------\
> > | a 5-disk RAID10 is better than a 6-disk RAID10 |
> > | ONLY IF your data is WORTH LESS than 3,524.3 |
> > | bucks. |
> > \------------------------------------------------/
> > any thoughts? i'm a newbie. i wonder how
> > industry people think?
>
> Don't forget that having more drives increases the odds of a failing
> drive. If you have infinite drives at any given moment infinite drives
> will fail. Anyway I wouldn't know how to calculate this.

by drive, you mean a spinning hard disk?

i'm not sure how "infinite" helps here even
theoretically.  e.g. say that every year, 76% of
disks fail.  in the limit as the number of disks
approaches infinity, then 76% of infinity is
infinity.  but, how is this useful?

> Most people are limited by money and space. Even if this isn't your
> problem you will always need an additional backup strategy. The hole
> system can fail.
> I run a system with 8 drives where two can fail and they can be hot
> swoped. This is a closed source SAS which I really like except the part
> being closed source. I don't even know what kind of raid is used.
>
> The only person I know who is running a really huge raid ( I guess 2000+
> drives) is comfortable with some spare drives. His raid did fail an can
> fail. Data will be lost. Everything important has to be stored at a
> secondary location. But they are using the raid to store data for some
> days or weeks when a server is calculating stuff. If the raid fails they
> have to restart the program for the calculation.

thanks a lot.  highly appreciate these tips about
how others run their storage.

however, i am not sure what is the takeaway from
this.  e.g. your closed-source NAS vs. a large
RAID.  they don't seem to be mutually exclusive to
me (both might be on RAID).

to me, a NAS is just a computer with RAID.  no?


> Facebook used to store data which is sometimes accessed on raids. Since
> they use energy they stored data which is nearly never accessed on blue
> ray disks. I don't know if they still do. Reading is very slow if a
> mechanical arm first needs to fetch a specific blue ray out of hundreds
> and put in a disk reader but it is very energy efficient.

interesting.