Linux RAID subsystem development
 help / color / mirror / Atom feed
From: Phillip Susi <phill@thesusis.net>
To: Piergiorgio Sartor <piergiorgio.sartor@nexgo.de>,
	Reindl Harald <h.reindl@thelounge.net>
Cc: Piergiorgio Sartor <piergiorgio.sartor@nexgo.de>,
	linux-raid@vger.kernel.org
Subject: Re: RAID-10 near vs. RAID-1
Date: Tue, 25 Jun 2024 15:00:39 -0400	[thread overview]
Message-ID: <87ikxw6e5k.fsf@vps.thesusis.net> (raw)
In-Reply-To: <ZmnZYgerX5g8S9Cp@lazy.lzy>

Piergiorgio Sartor <piergiorgio.sartor@nexgo.de> writes:

> As far as I know, but please correct me if
> I'm wrong, a Linux md RAID-10 *near* layout,
> with 2 devices, has identical data distribution
> as a RAID-1 with 2 devices.
> Meaning the 2 devices are a mirror.

That's correct.

> The difference, if I understood it correctly,
> is that the RAID-10 has chunks, and hence stripes,
> while the RAID-1 does not have stripes.
> Furthermore, the read operation on RAID-10 are
> interleaved, delivering (for SSDs) double
> sequential read speed (for 2 devices), while
> the RAID-1 can handle two independent (one per
> device) read stream, each with single device
> reading speed.

No, since the layout is exactly the same as raid1, large sequential
reads can not be sent to both drives at the same time.

Now a two disk raid-10 in the offset or far layout however, does
interleave the data across the drives so they can both be read at the
same time to increase throughput.


      parent reply	other threads:[~2024-06-25 19:00 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-06-11 18:31 RAID-10 near vs. RAID-1 Piergiorgio Sartor
2024-06-11 23:04 ` Reindl Harald
2024-06-12  0:14   ` Paul E Luse
2024-06-12  7:06     ` Reindl Harald
2024-06-12  7:18       ` Reindl Harald
2024-06-12 17:25     ` Piergiorgio Sartor
2024-06-12 17:22   ` Piergiorgio Sartor
2024-06-12 22:35     ` Reindl Harald
2024-06-12 23:46       ` Dragan Milivojević
2024-06-13  5:38         ` Reindl Harald
2024-06-13  7:30           ` Robin Hill
     [not found]           ` <CALtW_agtMXsss_Y=A2HH+D5zTceJ0jv5eWM5OeKiRZphvVeXZw@mail.gmail.com>
     [not found]             ` <599595a2-fa5e-45ca-b358-5fb573a8920e@thelounge.net>
2024-06-13 19:54               ` Dragan Milivojević
2024-06-13 20:18                 ` Reindl Harald
     [not found]                   ` <CALtW_ageds8cA-3CgbSNW5sFmRvWGmqoM0vA1vbi5LxWLhgt7g@mail.gmail.com>
2024-06-13 20:53                     ` Reindl Harald
2024-06-25 19:00     ` Phillip Susi [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=87ikxw6e5k.fsf@vps.thesusis.net \
    --to=phill@thesusis.net \
    --cc=h.reindl@thelounge.net \
    --cc=linux-raid@vger.kernel.org \
    --cc=piergiorgio.sartor@nexgo.de \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox