Re: Homebuilt NAS Advice
> No, I am talking about "Extra space taken, extra power used 24/7".
> An external device just does not use that much power
It can easily end up consuming about as much power as my BananaPi, so it
risks doubling the power consumption.
> or take a lot of space.
I suspect my wife would disagree.
>>>> Right, RAID-over-USB is of course going to blow my SSD-over-SATA out of
>>>> the water by a wide margin (not!).
>>> On the Banana Pi it can.
>> I'm not sure what makes you think so. In terms of bandwidth USB2 limits
> With some exceptions, the Pi boards use micro SD cards. They are
> slower than an external drive. I have confirmed that.
I'm talking about SSD-over-SATA, not SD cards.
I specifically chose boards using the A20 CPU (like the BananaPi)
because that SoC comes with a real SATA port (tho its driver was limited
to about 50MB/s write speed for some reason until a fairly recent kernel
patch).
> This thread is about a NAS, remember? By definition it is
> a repository of data.
Fair enough. We drifted to laptops and such, but indeed the subject
was NAS. So yes, I have data there (mostly music/photos/videos, and backups)
>>>> And if I keep my home partition in it, the "presto" comes with the
>>>> footnote "after you logout and log back in" (fun!)
>>> You lost me. Why log out?
>> In my experience unplugging a USB disk while it's mounted is a recipe
>> for hangs and replugging it will not always bring the partition back to life.
> Why do that? Boot the machine with the array attached.
Booting is something I do very rarely.
>>>> It's no different, indeed, except a bit more expensive and bigger.
>>> Well, OK. How much is down-time worth?
>> What down time?
>> You mean the time to walk over and grab my hot spare laptop?
> Which does not have the information on the failed laptop.
As mentioned at the beginning of the thread, the vast majority of the
files on are regularly pushed to a Git server or are under IMAP, so
anything older than a couple of hours (give or take) will be available
to the hot spare.
> If that information is at all important, it constitutes downtime
> to recover it. For a NAS, that can be pretty big.
The files on my servers change even much more slowly, so I sync the two
servers manually (by running an `rsync` script) whenever I put important
new info on them (i.e. new music/photos/videos).
>> Even more so when that downtime only happens once every 10 years or so
>> (my rate so far is a bit lower than that, but let's assume that a drive
>> of mine will fail tomorrow).
> I had to deal with six failed drives last month.
I've had to deal with 2 failed drives over my lifetime so far ;-)
>> No, I'm just saying that RAID will save me from this trouble once every
>> 10 years, but other things will still cause me to lose some of my work
>> several times a year, so the gain of RAID is a drop in the ocean.
> All I can say as a 40 year veteran in this industry is that is not
> my experience.
That's because your use cases are very different from mine (I don't
think the 5 years less than you of "veteranism" is the deciding factor).
>> As I said, downtime is minimal because I have other machines I can use
>> "on the spot".
> Again, not with the data from the failed system.
The only really valuable data that I produce is code, and when I lose the
last N hours of code I wrote, it takes me much less than N hours to
reproduce it. And drive failure is but one reason why I sometimes lose code.
> Yet again, missing any data on the old machine. If that data is not
> important, then fine, although it begs the question, "Why have a
> computer at all?" If a backup exists, then the data can be recovered onto
> the new system, but that takes *TIME*. Any data not on a backup must be
> manually recovered by reproducing the original work, and that can really
> take *TIME*. In my case, sometimes months. I am talking about a real-world
> scenario, here, which actually happened, not a hypothetical. I am also
> talking about five digits in terms of the cost.
I've been a sysadmin, and have used RAID then (there wasn't even
a question of using RAID or not). But different use-cases call for
different choices.
>> Yes, I agree that RAID can be handy in some contexts.
> No, it is *ESSENTIAL* whenever time and data are important.
Redundancy is essential, yes. RAID is one way to get redundancy.
Not the only one.
Stefan
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