From: Alexei_Roudnev (Alexei_Roudnev_at_exigengroup.com)
Date: Mon Nov 26 2007 - 23:12:11 CET
Message-ID: <07a001c83079$647f2790$7031a8c0@exigengroup.com> From: "Alexei_Roudnev" <Alexei_Roudnev@exigengroup.com> Date: Mon, 26 Nov 2007 14:12:11 -0800 Subject: Re: [suse-sles-e] Re: What is up with >2TB luns?
SATA drivers are not much slower vs. SAS drives (except on high intensity
random IO). Don't forget that, even if RPM is 7200 vs. 15K, the data density
is MUCH higher, and both SATA and SAS have sufficinet data transfer rate
over the bus (higher then disk can provide anyway).
Real tests don't show much difference in linear reading or writing on SATA
vs. SAS (and SATAs are, de facto, more reliable vs. SAS
if IO intensity is not very high - they are manufectured in much higher
volumes and are used by unskilled consumers who never backups their data.).
Huge difference appears if you began random IO and fill in SCSI with 10 - 20
outstanding IO requests so that drive can optimize IO.
----- Original Message -----
From: "Joseph Marton" <jmmarton@gmail.com>
To: <suse-sles-e@suse.com>
Sent: Thursday, November 22, 2007 6:58 AM
Subject: Re: [suse-sles-e] Re: What is up with >2TB luns?
> I'm trying to find out how he's even using 1TB disks. He said this is
> a Dell 2950 server. Well, look here:
>
> http://www.dell.com/content/products/productdetails.aspx/pedge_2950?c=us&cs=04&l=en&s=bsd&~section=specs#tabtop
>
> The largest drives they show for that server are 750GB SATA drives.
> And to top it off they are only 7200 RPM. So first he's got the
> performance hit of SATA instead of SAS, second the performance hit of
> 7200 RPM versus 10k or even 15k RPM. Sounds like this server really
> has a number of issues relating of storage even before attempting to
> determine a proper RAID configuration.
>
> Joe
>
> On 11/22/07, Ciro Iriarte <cyruspy@gmail.com> wrote:
>> PS: I bet your nice 1TB disks are slower that the little 72GB or 146GB
>> ones running at 10.000rpm, so you already have a performance hit
>> there....
>
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