Re: Reasonably simple setup for 1TB HDD and 250GB M.2 NVMe SSD
Em [2022-01-02 dom 23:38:48+0000], piorunz escreveu:
> On 02/01/2022 16:33, Jorge P. de Morais Neto wrote:
>> I am currently using compress-force=zstd:12 for the SSD and
>> compress=zstd:12 for both HDD (internal SATA and external USB3)¹.
>> Despite the strong compression level, performance is pretty good. Yet,
>> when the system settles, I intend to reduce compression level to 9 or 6
>> (as you earlier recommended). This should make performance even better,
>> while saving a lot of space because most data was compressed at
>> level 12.
>
> I run compress-force=zstd:6 on my fast PC, compress-force=zstd:3 on my
> server (to give it a bit more breathing space), and also same level 3 on
> my laptop. 12 is quite high for SSD, are you sure you not slowing down
> peak performance of your SSD by intense CPU usage? Or is it by design,
> to reduce number of writes to SSD?
Indeed I use such high compression to prolong SSD lifetime. IIUC,
besides directly reducing the amount of data written, compression allows
extra over-provisioning which should reduce the write amplification
factor too.
Level 12 compression probably hurts performance a bit, but programs
still start very quickly---far quicker than they did over the HDD with
ext4. This makes sense to me, because (IIUC) starting programs is
read-intensive and zstd decompression is fast even on high compression
levels. And surprisingly, even dpkg package installation and updates,
which (IIUC) are write-intensive, are very quick too.
Besides, I think I rarely need top CPU power and disk throughput at the
same time. I max out the quad-core processor when compiling Guix
packages but that happens on /tmp (tmpfs), so high Btrfs zstd
compression does no harm. I also stress the CPU (and the integrated
GPU) on the rare occasions I play Xonotic or SuperTuxKart, and Btrfs
compression probably does no harm during 3D game rendering either.
In conclusion, my SSD is plenty quick for my needs even with very high
Btrfs zstd compression. I care more about maximizing its lifetime than
having programs start a fraction of a second quicker when they already
start very quickly.
And when the system settles I intend to reduce Btrfs zstd compression
level to 9 or 6 in an attempt to save electricity---although I am nearly
always on AC power.
> No, I am not on this list, where is it? Please send a link!
http://vger.kernel.org/vger-lists.html#linux-btrfs
Kind regards,
Jorge
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