Am 12.06.24 um 19:22 schrieb Piergiorgio Sartor:
On Wed, Jun 12, 2024 at 01:04:18AM +0200, Reindl Harald wrote:
Am 11.06.24 um 20:31 schrieb Piergiorgio Sartor:
I'm setting up a system with 2 SSD M.2 (NVME).
I was wondering if would it be better, performace
wise, to have a RAID-10 near layout or a RAID-1.
Looking around I found only one benchmark:
https://strugglers.net/~andy/blog/2019/06/02/exploring-different-linux-raid-10-layouts-with-unbalanced-devices/
Which uses mixed SSD, NVME and SATA.
Does anybody have any suggestions, links, or
ideas on the topic?
BTW, practically speaking, what's the difference,
between the two RAIDs?
i wouldn't even consider a RAID10 with two disks, especially with SSD and
practically you end with a unsupported RAID1 because there are no stripes
with 2 disks
I'm a bit confused here. What do you mean
with "unsupported RAID1"?
well, the normal operation mode of a RAID10 isn't only 2 drives
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.
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.
how do you imagine stripes with only two drives?
stripes are "half of the file on disk 1, the other half on disk 2"
that's not possible with only 2 drives
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.
but how should this work with only 2 drives?
