RE: [Xen-devel] Disk difference (file, tap:aio ecc)

[Mike Viau <viaum@xxxxxxxxxxxxxxx>]

To:     Fantu <fantonifabio@xxxxxxxxxx>
Subject:     Re: [Xen-users] Difference between file and tap:aio
From:     Pasi Kärkkäinen <pasik@xxxxxx>
Date:     Fri, 9 Apr 2010 17:24:44 +0300
Cc:     xen-users@xxxxxxxxxxxxxxxxxxx
Delivery-date:     Fri, 09 Apr 2010 07:25:49 -0700

> Date: Thu, 8 Apr 2010 14:44:59 -0700
> From: fantonifabio@xxxxxxxxxx
> To: xen-devel@xxxxxxxxxxxxxxxxxxx
> Subject: [Xen-devel] Disk difference (file, tap:aio ecc)
>
>
> Someone can explain me good difference betwen different disk please? I not
> found good explain
> --
> View this message in context: http://old.nabble.com/Disk-difference-%28file%2C-tap%3Aaio-ecc%29-tp28184984p28184984.html
> Sent from the Xen - Dev mailing list archive at Nabble.com.
>

[quote]

file: uses dom0 kernel page cache, and thus might give better performance than 
phy: or tap:aio:,
but it's also more insecure because of the caching.

tap:aio: uses direct IO, so it bypasses dom0 kernel caches, and works like phy: 
in that sense.

blktap1 provides also other modes than :aio, like: qcow, but those were not 
very stable or fast,
so blktap2 was developed. for blktap1 see: 
http://wiki.xensource.com/xenwiki/blktap .

blktap2 also has vhd image support including snapshots and cloning.
See here: http://wiki.xensource.com/xenwiki/blktap2 .

-- Pasi

[/quote]

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