vinum vs. DPT smartcacheIV raid

Ean Kingston ean at
Wed Feb 16 15:52:28 GMT 2005

> On Wed, Feb 16, 2005 at 09:58:17AM -0500, Ean Kingston wrote:
>> > I have a box with DPT PM2044 SmartCacheIV UW-SCSI PCI cards which can
>> do
>> > RAID-5 in hardware, but I'd have to use the DOS volume manager to set
>> up
>> > the array. I have heard reports that vinum woudl be faster than using
>> the
>> > native card. Is this true?
>> Doubtful, though I have heard that there are some rare special
>> circumstances where software raid can be faster. Given your hardware,
>> you
>> will probably not experience those conditions.
> The reason I asked is because

I did not know that. Interesting read.

> suggests vinum can be marginally better than the hardware raid on the
> smartraid range of cards (which have an even faster processor onboard
> than the smartcache range). The CPU platform is more or less comparable.
> Then again it is with old Fbsd, so I don't know how accurate that is.

You may have noticed that there were comments about not trusting vinum's
RAID5 support in that article. If you are using FreeBSD 5.3, the default
is now gvinum (sort of second generation of vinum). The gvinum tools don't
give you the ability to create RAID5 virutal disks so if that is what you
want, you may not want to go with vinum or gvinum.

Another thing to consider is if you use software RAID and your application
gets CPU bound, you are going to take a double performance hit (both disk
and cpu).

I don't know your situation so it is your call.

>> > Should I not bother with doing the hardware
>> > raid
>> > and just go with vinum?
>> Use the hardware RAID, especially if you are going to use a simple RAID
>> configuration (like one big RAID-5 virtual disk). Just make sure you
>> have
>> some way of figuring out if one of the disks goes bad. Worst case you
>> could boot off a DOS floppy once in a while to make sure all the disks
>> are
>> still good.
>> > The rest of the system is a k6-2 400mhz with 256mb ram (amount might
>> > change).
>> > I will also have moderate network i/o on the pci bus (obviously).
>> --
>> Ean Kingston
>> E-Mail: ean_AT_hedron_DOT_org
>> URL:
> --
> Peter C. Lai
> University of Connecticut
> Dept. of Molecular and Cell Biology
> Yale University School of Medicine
> SenseLab | Research Assistant
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Ean Kingston

E-Mail: ean_AT_hedron_DOT_org

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