Re: [gentoo-user] LVM and moving things around

[Dale]

Laurence Perkins wrote:
>> -----Original Message-----
>> From: Dale <rdalek1967@×××××.com>
>> Sent: Monday, April 4, 2022 5:42 AM
>> To: gentoo-user@l.g.o
>> Subject: Re: [gentoo-user] LVM and moving things around
>>
>> Bill Kenworthy wrote:
>>> Rsync has a bwlimit argument which helps here. Note that rsync copies
>>> the whole file on what it considers local storage (which can be
>>> mounted network shares) ... this can cause a real slowdown.
>>> BillK
>>>
>>>
>> I ended up just letting it do its thing.  I didn't want to slow it down by much, just make my desktop able to respond better.  I used nice and ionice to do this with emerge and it works great.  I just thought I was missing some option for that command that google didn't help with.  I went and helped my sis-n-law with some garden stuff.  That helped.  ;-)
>>
>> As it stands now, I've copied enough over to get a free 8TB drive.  I set up LUKS, which includes LVM, on the drive and am copying some more files onto the newly encrypted drive.  Once everything is transferred, I'll then see if I need the other drive added or not.  I may not at the moment.  Of course, once fiber internet gets here, that may change pretty soon.
>>
>> If someone is really knowledgeable about LVM and LUKS and how to set up a encrypted hard drive, not a whole install but just a data drive, a howto for this would be really nice.  I had to use a LUKS howto and a LVM howto and sort of merge commands until I figured out how to get the two together.  Even tho I got it working, I'm still not real clear on how one part of it works.  I'm just not clear enough on it to write one myself.  A Gentoo wiki would be nice.  There's one for the two separately but not together.  One posted anywhere google can find it would be great tho.
>>
>> Now to find something to do while rsync copies over some 6TBs of files. O_O
>>
>> Dale
>>
>> :-)  :-)
>>
> A little late to the party, but the other setting to look at when you're doing this kind of thing is "sysctl vm.dirty_ratio".
> Basically it's what percentage of the disk cache can be dirty before the system forces all IO operations to be synchronous.
>
> Setting it higher lets the system keep more data up-in-the-air while you're shuffling lots of stuff around.  Of course, it also risks losing more if the system crashes in the middle of it all, so use it judiciously.
>
> Setting dirty_ratio dirty_background_ratio, and dirty_writeback_centisecs appropriately when doing things with large amounts of data can significantly improve system responsiveness and, with rotational drives, throughput.
>
> LMP


What's interesting, when it was doing the copy that made me ask about
this, it was bad slow.  It really hit anything KDE hard and Seamonkey
too.  Switching desktops with the mouse, real slow.  If I used the F*
keys, switched pretty fast. 

Today I was copying some more files from the normal old drive to the now
encrypted one.  It didn't slow anything down enough to matter and most
of the time, I couldn't even tell it was so busy.  I have no idea what
made the difference tho.  Maybe it was cosmic rays from Mars.  ROFL 

One thing that annoys me, it trying to use swap.  I don't want to
disable it because on occasion Firefox goes nuts and starting hogging
memory really bad.  I have swappiness set to like 5 or something which
means it shouldn't use it but when using rsync, it creeps some in.  When
it does, that results in some slowness.  I have a little script thing
that clears all that but still, I may set it to 3 or maybe 2 for a bit. 
Me ponders the thought. 

I'm making progress.  Feel sorry for those hard drives tho. ;-)

Dale

:-)  :-)