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<P><FONT SIZE=2>Except that swraid does usually not support hotswap replacing of a failed drive without interrupting the server's current workload and without an admin logging in and doing some risky mdadm / scsidriver surgery.<BR>
<BR>
Michael <BR>
<BR>
Sent from my GoodLink synchronized handheld (www.good.com)<BR>
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<BR>
-----Original Message-----<BR>
From: Mark Hahn [<A HREF="mailto:hahn@mcmaster.ca">mailto:hahn@mcmaster.ca</A>]<BR>
Sent: Wednesday, November 21, 2007 05:27 PM Pacific Standard Time<BR>
To: Ekechi Nwokah<BR>
Cc: beowulf@beowulf.org<BR>
Subject: Re: [Beowulf] Software RAID?<BR>
<BR>
> Does anyone know of any software RAID solutions that come close to the<BR>
> performance of a commodity RAID card such as LSI/3ware/Areca for<BR>
> direct-attached drives?<BR>
<BR>
yes, MD, the standard Linux software raid, is generally faster<BR>
than HW raid. yes, this can be argued, though not in any kind<BR>
of slam-dunk. as far as I know, the very fastest HW raid (3ware<BR>
and areca - I wouldn't guess LSI) top out at 6-800 MB/s.<BR>
obviously, MD will consume some cycles supporting that kind of<BR>
bandwidth, but it can be done.<BR>
<BR>
for a typical cost-sensitive fileserver, especially if only over<BR>
a gigabit or two, MD is a no-brainer. It Just Works and most any<BR>
MB will already have ~6 sata ports, so you just plug in some<BR>
disturbingly cheap 320-1000G sata disks (~60 MB/s each), and<BR>
you're flying.<BR>
<BR>
> With the availability multi-core chips and SSE instruction sets, it<BR>
> would seem to me that this is doable.<BR>
<BR>
SW raid has generally been the right choice for 5+ years -<BR>
since the host got fast memory interfaces, basically.<BR>
even the earliest MMX helped out with this stuff. and the host<BR>
CPU is always going to be many times faster than the little<BR>
embedded core on a HW raid card.<BR>
<BR>
> Would be nice to not have to pay<BR>
> for those RAID cards if I don't have to. Just wondering if anything<BR>
> already exists.<BR>
<BR>
<A HREF="http://linux.yyz.us/why-software-raid.html">http://linux.yyz.us/why-software-raid.html</A><BR>
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