From: | Jim Nasby <Jim(dot)Nasby(at)BlueTreble(dot)com> |
---|---|
To: | Bill Moran <wmoran(at)potentialtech(dot)com>, Félix GERZAGUET <felix(dot)gerzaguet(at)gmail(dot)com> |
Cc: | <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: Test disk reliability (or HGST HTS721010A9E630 surprisingly reliable) |
Date: | 2015-12-23 02:36:44 |
Message-ID: | 567A08BC.80704@BlueTreble.com |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-general |
On 12/21/15 8:22 AM, Bill Moran wrote:
>>> Why? Just because a disk isn't enterprise-grade doesn't mean it has to lie
>>> > >about fsync, which is the only thing diskchecker.pl tests for.
>>> > >
>> >
>> >I was thinking that since the disk have a 32M write-cache (with not
>> >battery) it would lie to the OS (and postgres) about when data are really
>> >on disk (not in the disk write cache). But maybe that thinking was wrong.
There are ways to make on-disk write caches safe without a battery. IIRC
some hard drives would use the inertia of the platter (turning the motor
into a generator) to write contents out on power-off. You could also use
a "super cap".
> It varies by vendor and product, which is why diskchecker.pl exists.
> It's even possible that the behavior is configurable ... check to see
> if the vendor provides a utility for configuring it.
Your OS might let you control it too; I know FreeBSD has support for
this. (Whether the drive obeys or not is a different matter...)
--
Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX
Experts in Analytics, Data Architecture and PostgreSQL
Data in Trouble? Get it in Treble! http://BlueTreble.com
From | Date | Subject | |
---|---|---|---|
Next Message | Jim Nasby | 2015-12-23 02:44:37 | Re: Table with seemingly duplicated primary key values |
Previous Message | oleg yusim | 2015-12-23 00:03:32 | Re: Shared system resources |