Re: software or hardware RAID?

On 28/03/19, Perumal Raj (perucinci(at)gmail(dot)com) wrote:
> On Sat, Mar 23, 2019 at 3:12 PM Kenneth Marshall <ktm(at)rice(dot)edu> wrote:
> > On Sat, Mar 23, 2019 at 12:09:11PM +0000, Rory Campbell-Lange wrote:
> > > On 17/03/19, Rory Campbell-Lange (rory(at)campbell-lange(dot)net) wrote:

> > > > We aren't sure whether to use software MDRaid or a MegaRAID card.
...
> > > > We use MDRaid elsewhere but we've never used it for our databases
> > > > before.
> > >
> > > Apologies for re-heating this email from last week. I could really
> > > do with the advice.
> > >
> > > Has anyone got any general comments on whether software RAID or an
> > > LSI card is preferable?

...

> > The main reason, in my opinion, to use a HW RAID card is for the NVRAM
> > battery backed cache to support writing to traditional spinning disks.
> > Since your SSDs have power-loss support, you do not need that and the HW
> > RAID controller. For database use, you would almost certainly be using
> > RAID 10 and software RAID 10 is extremely performant. I am in the middle
> > of setting up a new system with NVMe SSD drives and HW RAID would be a
> > terrible bottle-neck and software RAID is really the only realistice
> > option.

> Just would like to know conclusion here ,
>
> What is best RAID method (Software Or Hardware) for Postgres DB and what
> level ?

Hi Perumal

Ken's comments summarise the general tenor of the advice I've been
given.

Rory