[conspire] external storage recommendation

tom r lopes tomrlopes at gmail.com
Sat Sep 25 15:50:23 PDT 2021


No you are not asking that much.

Build your own!

Thomas

On Sat, Sep 25, 2021, 2:56 PM paulz at ieee.org <paulz at ieee.org> wrote:

> So when I am getting the NAS box, I want at least 2 bays.
>
> It comes down to how much actual storage I need and how much it costs.
> Raid 5 will require a more expensive box and several more disk drives.  So
> it is not obvious which will give the best total price per bit.
>
> And I probably want to steer clear of brands touting that they have all of
> the fancy software installed.  A reviewer of one model complained that
> after he bought NAS to have on his own network, the only way to access his
> personal data was through the website of WD.
>
> In my definition, my NAS should appear to my computer as a drive that can
> be accesses as easily as the internal drive, after things are set up.  This
> independent of the OS on the computer.   Am I asking too much?
>
>
>
> On Saturday, September 25, 2021, 01:41:10 PM PDT, Rick Moen <
> rick at linuxmafia.com> wrote:
>
>
> Quoting Paul Zander (paulz at ieee.org):
>
> > Raid 1 uses 2 drives with all data written to both.   Protection of
> > loss of 1 drive, but only get storage area of 1 drive.  For RAID to be
> > "efficient" 4 or more drives are needed.    Did I get that right?
>
> Head of the class, sir!  (Technically, RAID5 requires at least _3_
> drives.)
>
> The significant advantage of RAID1 mirroring over RAID5 & similar is
> simplicity and lower computational overhead (especially, but not
> exclusively, during a rebuild cycle following failure and replacement
> of a drive).  So, in many scenarios, those RAID1 advantages are
> compelling and make the 50% "loss" of capacity of little consequence and
> easy to justify.
>
> With (say) RAID5, you have around "loss" of capacity equal to the
> capacity of one of the constituent drives.
>
> Here is a FAQ:  https://www.vantagetech.com/faq/raid-5-recovery-faq.html
>
>
> I alluded earlier to ZFS (and its slightly lackluster Linux-native
> imitator, btrfs) as being in a different category relative to regular
> *ix filesystems like ext4, in ways that make it much more desirable for
> servers.  I should elaborate.
>
> ext4 is an excellent, high-performing, conservatively designed *ix
> filesystem.  There is nothing wrong with it.  Things it doesn't do, and
> doesn't aspire to do, include:
>
> o  background fsck and auto-repair / self-healing during normal system
> operation
> o  checksumming and vetting of every byte written, data and metadata
> o  data snaphots and replication
> o  native volume management
> o  native handling of RAID
> o  automatic rollback, in the event of detected error or inconsistency
> o  native data compression and de-duplication
> o  a lot more.  see https://en.wikipedia.org/wiki/ZFS#Summary
>
> A regular *ix filesystem, even a really good one like ext4, has none of
> those things built-in.  As filesystem sizes and data collections
> (e.g., A/V files) get bigger and bigger, the risks from bitrot and
> data corruption silently occurring and accumulating over time become
> more worrisome, and also the risk of having multiple days of system
> downtime just because of need to correct filesystem errors during a
> reboot-driven fsck -- because you had 10 terabytes of files.
>
> The whole idea of a file _server_ on your network is supposed to be for
> it to be a _reliable_ place to house your files, which is where the
> first two ZFS advantages listed really shine.  On the minus side, ZFS is
> fairly RAM-thirsty.  So, arguably worth the RAM overhead.
>
> ZFS was one of several ground-breaking Sun Microsystems projects that
> gave Solaris and several compatibly licensed BSDs a functionality edge
> over Linux.  The others were dtrace (which is kernel-level debugging),
> Solaris Containers aka Zones (which are a better implementation of
> chroot jails), a Kernel-based Virtual Machine, and OpenSolaris Network
> Virtualization and Resource Control aka Crossbow (a set of features that
> provides an internal network virtualization and quality of service).
> All of those are C-coded in the Solaris kernel under CDDL terms, which
> clashes with Linux's GPLv2 terms, hence the code, even if ported to the
> Linux kernel, cannot be lawfully distributed in binary form, as that
> would be copyright violation.[1]
>
> btrfs is an independent attempt to implement most of ZFS's features in
> Linux.  However, even now, 14 years after its debut, it still has some
> problems.  Here, this runthrough will tell you about that, better than I
> could:
>
> https://arstechnica.com/gadgets/2021/09/examining-btrfs-linuxs-perpetually-half-finished-filesystem/
>
>
>
>
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