From: "Nikolay A. Fetisov" <naf@naf.net.ru>
To: hardware@lists.altlinux.org
Subject: Re: [Hardware] SDA Write cache doesn't support DPO or FUA
Date: Mon, 03 Dec 2012 11:43:00 +0400
Message-ID: <1354520580.1269.25.camel@v3405.naf.net.ru> (raw)
In-Reply-To: <1354481997.24727.3.camel@localhost.localdomain>
В Пн, 03/12/2012 в 00:59 +0400, gBopHuk_alt пишет:
> Тут словил такую штуку в syslog
>
> sda: write cache: disabled read cache: enabled, doesn't support DPO or
> FUA
>
> Кто-нибудь в курсах что это за штуки и зачем они?
Согласно всезнающему Google, это флаги команд чтения данных SCSI:
http://en.wikipedia.org/wiki/SCSI_Read_Commands
"Disable Page Out (DPO) allows the initiator to warn the target that the
data being read is unlikely to be requested again soon and so is not
worth keeping in the target's data cache.
Force Unit Access (FUA) tells the target to fetch the data from the
media surface and to not use a cached copy."
Т.е., рекомендация устройству не сохранять считанное в своём кэше (DPO),
и требование прочитать данные с устройства, даже если они есть в кэше
(FUA).
--
С уважением,
Николай Фетисов
next prev parent reply other threads:[~2012-12-03 7:43 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-02 20:59 gBopHuk_alt
2012-12-03 7:38 ` Michael Shigorin
2012-12-03 7:43 ` Nikolay A. Fetisov [this message]
2012-12-03 9:20 ` Michael Shigorin
2012-12-03 10:30 ` gBopHuk_alt
2012-12-03 10:56 ` Alexey Borisenkov
2012-12-03 17:10 ` gBopHuk_alt
2012-12-03 18:28 ` Alexey Borisenkov
2012-12-04 1:36 ` gBopHuk_alt
2012-12-04 9:09 ` Nikolay A. Fetisov
2012-12-06 12:39 ` gBopHuk_alt
2012-12-13 18:38 ` gBopHuk_alt
2012-12-13 18:37 ` Alexey Borisenkov
2012-12-13 19:14 ` gBopHuk_alt
2012-12-13 19:26 ` Alexey Borisenkov
2012-12-13 19:39 ` gBopHuk_alt
2012-12-13 19:42 ` Alexey Borisenkov
2012-12-13 20:17 ` gBopHuk_alt
2012-12-13 20:23 ` Alexey Borisenkov
2012-12-14 18:14 ` Michael Shigorin
2012-12-14 22:09 ` gBopHuk_alt
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