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From: Thomas Jarosch <thomas.jarosch@intra2net.com>
To: Andrei Banu <andrei.banu@redhost.ro>
Cc: linux-raid@vger.kernel.org
Subject: Re: Incredibly poor performance of mdraid-1 with 2 SSD Samsung 840 PRO
Date: Thu, 25 Apr 2013 13:38:17 +0200	[thread overview]
Message-ID: <15025553.voJ1cqAbWd@storm> (raw)
In-Reply-To: <51732422.1050109@redhost.ro>

On Sunday, 21. April 2013 02:26:26 Andrei Banu wrote:
> They are connected through SATA2 ports (this does explain the read speed
> but not the pitiful write one) in AHCI.

So the SATA controller is already in AHCI mode. Good.

You didn't say what kind of server hardware you are using or I missed it.
On the HP DL3xxx servers we usually use, we have to enable AHCI mode _and_ 
the write cache in the BIOS. Maybe your server needs something similar.

Some RAID controllers only allow you to enable the write cache
when a battery-backed write cache module is installed.

HTH,
Thomas


  parent reply	other threads:[~2013-04-25 11:38 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-04-19 22:58 Incredibly poor performance of mdraid-1 with 2 SSD Samsung 840 PRO Andrei Banu
     [not found] ` <CAH3kUhEaZGON=fAyVMZOz5fH_DcfKv=hCa96UCeK4pN7k81c_Q@mail.gmail.com>
2013-04-20 23:26   ` Andrei Banu
     [not found]   ` <51725458.7020109@redhost.ro>
     [not found]     ` <CAH3kUhHxBiqugFQm=PPJNNe9jOdKy0etUjQNsoDz_LJNUCLCCQ@mail.gmail.com>
2013-04-20 23:25       ` Andrei Banu
2013-04-20 23:26       ` Andrei Banu
2013-04-21  2:48         ` Stan Hoeppner
2013-04-21 12:23           ` Tommy Apel
2013-04-21 16:48             ` Tommy Apel
2013-04-21 19:33             ` Stan Hoeppner
2013-04-21 19:56               ` Tommy Apel
2013-04-22  0:47                 ` Stan Hoeppner
2013-04-22  7:51                   ` Tommy Apel
2013-04-22  8:29                     ` Tommy Apel
2013-04-22 10:26                     ` Andrei Banu
2013-04-22 12:02                       ` Tommy Apel
2013-04-23  2:59                         ` Stan Hoeppner
2013-04-22 23:21                     ` Stan Hoeppner
2013-04-25 11:38         ` Thomas Jarosch [this message]
2013-04-21  0:10 ` Stan Hoeppner
     [not found] ` <51732E2B.6090607@hardwarefreak.com>
2013-04-21 20:46   ` Andrei Banu
2013-04-21 23:17     ` Stan Hoeppner
2013-04-22 10:19       ` Andrei Banu
2013-04-23  2:51         ` Stan Hoeppner
2013-04-23 10:17           ` Andrei Banu
2013-04-24  3:24             ` Stan Hoeppner
2013-04-24  8:26               ` Andrei Banu
2013-04-24  9:12                 ` Adam Goryachev
2013-04-24 10:24                   ` Tommy Apel
2013-04-24 21:42                     ` Andrei Banu
2013-04-24 21:40                   ` Andrei Banu
2013-04-24 16:37                 ` Stan Hoeppner
2013-04-24 21:46                   ` Andrei Banu
     [not found]                     ` <CAH3kUhHnF0imY=CAHfzaQy4XJuOMgOtbHNp17EYzeSJR2en7Fg@mail.gmail.com>
2013-04-25 10:11                       ` Andrei Banu
2013-04-25 10:56                     ` Stan Hoeppner
2013-04-22 23:11       ` Andrei Banu
2013-04-23  4:39         ` Stan Hoeppner
2013-04-22 23:25       ` Stan Hoeppner
2013-04-23  4:49         ` Mikael Abrahamsson
2013-04-23  6:01 ` Stan Hoeppner

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