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Re: Slow writes to disk




How does your partition alignment look for that disk?
Or, in other words, what does 'fdisk -l' tell you about this one?

Am 02.11.18 um 13:31 schrieb Stefan Monnier:
> For a while now I noticed that aptitude is very slow on one of my
> machine (Thinkpad T61) running Debian testing.  At first I thought it
> was because its disk (a fairly old 120GB SSD) was suffering from some
> kind of problem, so I replaced it with an almost new 240GB Samsung 840.
> 
> It seemed to bet better at first, but maybe it was just an impression.
> In any case, now it's definitely very slow.  Digging more into it,
> I found out that part of the problem seems to be very slow writes to
> the disk.  I can reproduce tests where `dd`ing a 40MB file proceeds at
> the ridiculous speed of about 500KB/s (tho sometimes the speed is much
> higher).
> 
> I've been using SSD drives on most of my machines for many years now,
> and it's the first time I notice such a slow performance.  `smartctl`
> shows that the drive an not registered any errors at all and has a "wear
> leveling" of 18.
> 
> I figured maybe the drive is having trouble for lack of free space which
> leads to high load on the "GC", so I did a `fstrim` on / and /home
> (both on LVM), which took a bit of time and returned without any
> message, which I took to be a positive sign that it managed to do what
> it's supposed to.  But it made no difference to the performance.
> 
> Any idea?
> 
> 
>         Stefan
>