Mailinglist Archive: opensuse-factory (439 mails)

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Re: [opensuse-factory] Adding SSDs?
  • From: Jason <relentropy@xxxxxxxxx>
  • Date: Thu, 13 Mar 2014 18:25:19 -0400
  • Message-id: <1910293.xNsThXksVo@host.laptop>
On Thursday, March 13, 2014 10:06:08 you wrote:
On Thu, Mar 13, 2014 at 9:26 PM, Jason <relentropy@xxxxxxxxx> wrote:
As for the discard, few people have told me in the past few days not to
use it and considering they know what they're talking about I'm not
questioning it so I have personally removed it.

The only reason I can think of that someone would suggest not using
discard is that it can impact the speed of deleting content off the
drive. https://patrick-nagel.net/blog/archives/337 Basically, it
depends on your use case for the data you're working with if discard
is something you don't want to use. For me, using "discard" has a
negligible impact - I don't see the difference in my day-to-day use,
and it's an easy solution vs setting up the cron job.

Using discard... you need kernel 2.6.33 or higher and an SSD that
supports trim (ie any modern drive should do this).

Using fstrim on a cron job.. is just as effective.

Sensible flags for btrfs on ssd are noatime,autodefrag,compress=lzo and
that is coming from a person who works on btrfs.

There is disagreement about noatime... many suggest it's a lot better
to use relatime. If you use noatime, you can negatively impact some
applications that depend on the into - mutt is a prime example.

Hmm, maybe I was too definitive. wrt to flags, this is on _my_ personal
machines relevant to their use cases. I do find writing access times as
unnecessary overhead and it hasn't bitten me. (yet) But yes, relatime is a
better solution in general.

Thank you for expanding, it is useful info.

Yes. But SSDs haven't really changed that much, the basics are still the
same and reliability went up and down and up again, depending on the
time.
Ah, but they have. The firmware is vastly different and the the types
and quantity of nand chips in use have also changed (eg older MMC nand
vs newer TLC nand)

Not that _much_ different from 2nd gen onward, the methodology is still the
same, only algoritms and operations have been honed further so the articles do
apply despite their age. Though I haven't dissected nor would I know how to:)

As for TLC, I'm not _yet_ convinced. The finesse required to deal with so many
gates (voltages) and the inherent latency is something I find hard to believe
it will _just work_ for say at least 5 years.

There is a reason SLC is server grade and MLC is widely adopted for consumer
drives, TLC is (currently) simply a method to drive the price down. Just IMHO.


C.

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