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Date: Mon, 24 Feb 2014 03:27:16 -0300
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Subject: [gentoo-user] RAID 1 vs RAID 0 - Read perfonmance
From: Facundo Curti <facu.curti@gmail.com>
To: gentoo-user@lists.gentoo.org
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Hi. I am again, with a similar question to previous.
I want to install RAID on SSD's.
Comparing THEORETICALLY, RAID0 (stripe) vs RAID1 (mirrior). The performance
would be something like this:
n=3D number of disks
reads:
raid1: n*2
raid0: n*2
writes:
raid1: n
raid0: n*2
But, in real life, the reads from raid 0 doesn't work at all, because if
you use "chunk size" from 4k, and you need to read just 2kb (most binary
files, txt files, etc..). the read speed should be just of n.
On the other side, I read over the net, that kernel don't support
multithread reads on raid1. So, the read speed will be just n. Always. =C2=
=BFIt
is true?
Anyway, my question is. =C2=BFWho have the best read speed for the day to d=
ay?
I'm not asking about reads off large files. I'm just asking in the "normal"
use. Opening firefox, X, regular files, etc..
I can't find the guide definitive. It allways are talking about
theoretically performance, or about "real life" but without benchmarks
or reliable data.
Having a RAID0 with SSD, and following [2] on "SSD Stripe Optimization"
should I have the same speed as an RAID1?
My question is because i'm between. 4 disks raid1, or RAID10 (I want
redundancy anyway..). And as "raid 10" =3D 1+ 0. I need to know raid0
performance to take a choice... I don't need write speed, just read.
=C2=BFAnyone knows the true about this? =C2=BFSomebody tried this?
Thanx a lot.!! Bytes! ;)
[1]http://www.pcstats.com/articleview.cfm?articleid=3D890&page=3D5
[2]
http://www.overclock.net/t/484367/guide-all-you-ever-wanted-to-know-about-r=
aid
--20cf305e23991c380404f32110d7
Content-Type: text/html; charset=UTF-8
Content-Transfer-Encoding: quoted-printable
<div dir=3D"ltr"><div>Hi. I am again, with a similar question to previous.<=
/div><div><br></div><div>I want to install RAID on SSD's.</div><div><br=
></div><div>Comparing THEORETICALLY, RAID0 (stripe) vs RAID1 (mirrior). The=
performance would be something like this:</div>
<div><br></div><div>n=3D number of disks</div><div><br></div><div>reads:</d=
iv><div>=C2=A0=C2=A0raid1: n*2</div><div>=C2=A0=C2=A0raid0: n*2</div><div><=
br></div><div>writes:</div><div>=C2=A0=C2=A0raid1: n</div><div>=C2=A0=C2=A0=
raid0: n*2</div><div><br></div><div>But, in real life, the reads from raid =
0 doesn't work at all, because if you use "chunk size" from 4=
k, and you need to read just 2kb (most binary files, txt files, etc..). the=
read speed should be just of n.</div>
<div><br></div><div>On the other side, I read over the net, that kernel don=
't support multithread reads on raid1. So, the read speed will be just =
n. Always. =C2=BFIt is true?</div><div><br></div><div>Anyway, my question i=
s. =C2=BFWho have the best read speed for the day to day? I'm not askin=
g about reads off large files. I'm just asking in the "normal"=
; use. Opening firefox, X, regular files, etc..</div>
<div><br></div><div>I can't find the guide definitive. It allways are t=
alking about theoretically performance, or about "real life" but =
without benchmarks or=C2=A0reliable data.<br></div><div><br></div><div>Havi=
ng a RAID0 with SSD, and following [2] on "SSD Stripe Optimization&quo=
t; should I have the same speed as an RAID1?<br>
</div><div><br></div><div>My question is because i'm between. 4 disks r=
aid1, or RAID10 (I want redundancy anyway..). And as "raid 10" =
=3D 1+ 0. I need to know raid0 performance to take a choice... I don't =
need write speed, just read.<br>
</div><div><br></div><div><div>=C2=BFAnyone knows the true about this? =C2=
=BFSomebody tried this?</div></div><div><br></div><div>Thanx a lot.!! Bytes=
! ;)</div><div><br></div><div>[1]<a href=3D"http://www.pcstats.com/articlev=
iew.cfm?articleid=3D890&page=3D5">http://www.pcstats.com/articleview.cf=
m?articleid=3D890&page=3D5</a></div>
<div>[2]<a href=3D"http://www.overclock.net/t/484367/guide-all-you-ever-wan=
ted-to-know-about-raid">http://www.overclock.net/t/484367/guide-all-you-eve=
r-wanted-to-know-about-raid</a></div><meta http-equiv=3D"content-type" cont=
ent=3D"text/html; charset=3Dutf-8"><meta http-equiv=3D"content-type" conten=
t=3D"text/html; charset=3Dutf-8"></div>
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