Keith C. Perry via plug on 4 Jan 2022 09:15:06 -0800

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Re: [PLUG] Moving mdadm RAID-5 to a new PC

Similar to Bhaskar, I would say that if the OP is considering SBC's for I/O heavy projects, I would recommend first considering a different SBC.  There are a number of  units that have PCIE connectivity if you are willing to pay a bit more.

Ultimately though, Rich F (et al) made a major point about network bandwidth that should not be understated.  Even in the HPC world people often do not seriously consider their network until after they've spent all their budget on the shiny new ginormous storage system.  That's not going to give the desired performance in the long run if your available network bandwidth isn't appropriate.  Typically, that's going to at least mean bonding multiple 1Gbs ports if not multiple 10Gbs points.  The name of that game is multiple ports first, then higher bandwidth ports if you can, if multiple people and services are going to be using the NAS simultaneously.

When you consider that, for a NAS, Rich M's idea about an old PC works well because you can get a 4x1Gb NIC and a decent multi-port SATA or proper RAID card for not a lot of money.  If you're going t a distributed system like Ceph then using SBC storage nodes is really slick but you really REALLY need network bandwidth since your head node (i.e. the metadata and the system "brains") is on separate node.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
Keith C. Perry, MS E.E.
Managing Member, DAO Technologies LLC
(O) +1.215.525.4165 x2033
(M) +1.215.432.5167

From: "K.S. Bhaskar via plug" <>
To: "PLUG" <>
Sent: Monday, January 3, 2022 2:33:22 PM
Subject: Re: [PLUG] Moving mdadm RAID-5 to a new PC

– Bhaskar

On Mon, Jan 3, 2022 at 2:17 PM Martin Cracauer via plug <> wrote:
Adam Zion via plug wrote on Mon, Jan 03, 2022 at 10:30:24AM -0500:
> Long story short: I have recently set up a home NAS on a Raspberry Pi 2 via
> mdadm. It works splendidly, if slowly. Hence wondering if it'd make sense
> to migrate it to a faster Pi. Has anyone done this before? Or would I be
> better off leaving the RAID where it is and moving all other services- like
> the streaming media server or Pi-hole ad blocker- onto another host?

The Raspberry Pi compute module 4 has a PCIe x1 slot.  You could run a
SATA multiport controller with that.  Or a stronger USB
multi-controller card.

As a general note, if you leave the raid on the very slow I/O I am
concerned about array rebuild time if you ever have to replace a
disk.  How long does a scrub take you?

Martin Cracauer <>
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