Re: Hardware for a back up server? [WAS Re: How to use dmsetuup?]
On 11/11/23 08:52, Andrew M.A. Cater wrote:
On Fri, Nov 10, 2023 at 10:22:07PM -0500, gene heskett wrote:
On 11/10/23 19:46, David Christensen wrote:
On 11/8/23 02:20, gene heskett wrote:
And I just looked at tht pair, and acc gparted they have both been
pvcreated, so I'll leave then alone and steal the dvd cable, puttin
a new 2T drive if I can rig power to it.
As I previously suggested, and as you previously seemed agreeable to, I
think you should stop working on the Asus and build a backup server.
I'm thinking of making a slow one out of a headless bananapi-5 with a 2T on
every usb3 port as a raid, type to be determined, I rather like the idea of
parity being striped across all 4 disks. I have the drives but not sure of
the usb-sata adapters, need to goto the garage and retrieve that box. That,
and there's only one of me ;o)> And me is 89 yo with a worn out body. A
pacemaker and some new parts in my heart too.
Are these 2TB SSDs or hard disks? I would counsel very strongly indeed
against using any ARM-based single board computer as a RAID device on
USB connections - they're just *not* up to it.
On 11/11/23 09:05, Stefan Monnier wrote:
> I don't think the issue is whether they're ARM based.
>
> The issue is simply how you connect the disks: in my experience, disks
> connected via USB are simply not quite up to a 24/7 situation,
> especially if the disk is USB-powered.
On 11/11/23 09:37, Pocket wrote:
> I have used ssd drives connected to a RPI4 ever since the 4 came out,
> zero issues.
>
> The RPI4's boot from the ssd drives.
>
> I have 4 SSD drives connected to a single RPI4 currently, using a
> powered USB hub.
>
> One of those drives contains the boot and root filesystems.
>
> BTW that particular RPI4 runs 24/7 as it is my name server, email
> server, web server and backup server for my network.
>
> It has an uptime of 18 months.
On 11/11/23 10:47, Stefan Monnier wrote:
> Hmm... so maybe the USB connection is not directly relevant either
> and the real issue is the power?
An obvious difference between internal and external drives is physical
protection. Internal drives and cables are protected. Everything gets
power from the same source (PSU, PCU fed by dual PSU, etc.). External
drives, cables, and power adapters can be moved, yanked, disconnected,
dropped, kicked, subjected to electrostatic discharge, etc.. There are
more parts to fail and more opportunities for failure with external
drives than with internal drives.
It is not uncommon for communications establishment to fail with
external drives. Similarly, communications re-establishment when the
computer and/or drive resume from a power saving mode. Writing and
testing this kind of software is difficult and you need people with both
both CS and EE skills. There is an astronomical number of combinations
to design and test for. The code runs rarely. For reliable 24x365
operations, the challenge is eliminating everything that can cause
communications establishment/ re-establishment -- operator steps,
computer configuration, drive configuration, power failures, cooling
failures, etc.. If you can find and eliminate all of them, a USB
external drive can stay connected a very long time.
Get a cheap barebones system that you add memory to in a small-ish size
case with SATA cables to motherboard ports that's Intel/AMD based that
you can then put disks into to format. If you can't get a barebones,
at least get a second hand machine in a tower case.
I have always liked ATX tower cases with lots of drive bays, both
internal and external. Over time, more products have become available
with good cooling and low noise. I have not found a major computer
manufacturer who makes servers with all of those features, so I build my
own:
* Fractal Design Define R5 case
* 3 @ Fractal Design low-speed 140 mm fans
* Fractal Design Ion+ 2 Platinum 660 W power supply
* Intel S1200V3RP motherboard
* Intel Xeon E3-1200 v3 series processors
* Dual channel ECC memory
* LSI 9207-8i HBA with "IT mode" non-RAID firmware
* Seagate Barracuda and Constellation ES.2 HDD's
* Intel 520 Series SSD's
* StarTech 2.5" and 3.5" mobile racks
* Cable Matters black SATA 6 Gbps cables with locking connectors
They are not cheap, small, or light, but they perform well, are easy to
work on, are reasonably quiet, and everything stays cool. They have
plenty of capacity for future upgrades.
Build a simple Debian system on one disk there to format other disks :)
I put my Debian and FreeBSD instances on a single 2.5" SATA SSD. I keep
them small -- 1 GB boot, 1 GB swap, and 12 GB root. I keep my system
configuration files and working files in a version control system (CVS).
Once you've built a simple Debian system there, you can add mdadm RAID
and use it as a backup storage device to copy off your /home and so on.
For my file server and backup server, primary storage is a ZFS stripe of
HDD mirrors (e.g. RAID10) with SSD cache and SSD mirror deduplication.
SSD RAID10 is very impressive when everything else matches. Backups
over a Gigabit LAN onto SATA III SSD RAID10 does not make sense because
Gigabit Ethernet is rated for 1 Gbps read/ write and a SATA III SSD
RAID10 is rated for 24 Gbps read and 12 Gbps write. I would put HDD's
in the backup server and put the SSD's in the workstation.
David
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