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Author Adaptec 2810SA extremely fast or extremely slow?
Fondazione Distrofici Onlus

2007-09-05, 1:19 pm

Hi, sorry for bad english..
I've got a Tyan Thunder S2885 and an Adaptec 2810SA, configured as
follows:

- 5 Maxtor 300gb hard disks on adaptec card
- 1 Maxtor 160gb hard disk attached to the motherboard
- 3 RAID5 volumes (partitions) on adaptec card
- 1 partition 1TB
- 1 partition 160 GB
- 1 partition 5GB

After executing a benchmark test, the results surprised me...

All the volumes of the Adaptec card showed the same results:
________________________________________
____________________
READING
- sequential reading (large files): 133 MB/s
- random reading (large files): 103 MB/s

- sequential reading (small files): 59 MB/s
- random reading (small files): 54 MB/s

________________________________________
____________________
WRITING
- sequential writing (large files): 10 MB/s
- random writing (large files): 8 MB/s

- sequential writing (small files): 7 MB/s
- random writing (small files): 8 MB/s

Aren't these results strange for what is said to be an "ideal cost-
effective solution for applications where high levels of sustained
read and write performance are required, including video streaming,
web content, reference data and fixed content storage" ??

What can I do?? I am writing an application that does video
acquisition in real time...

Thanks a lot,
Marco

the wharf rat

2007-09-06, 1:14 pm

In article <1189011849.248202.309560@d55g2000hsg.googlegroups.com>,
Fondazione Distrofici Onlus <info@disys.it> wrote:
>
> ________________________________________
____________________
>WRITING
>- sequential writing (large files): 10 MB/s
>- random writing (large files): 8 MB/s
>
>- sequential writing (small files): 7 MB/s
>- random writing (small files): 8 MB/s


10MB/sec for random writes in a raid 5 doesn't sound that
far off to me... The ideal situation is very large sequential writes.
Check that you have the write cache enabled. Make sure that command queueing
is enabled and not set to 1.

If your application is very write intensive IMHO you should use
RAID 10 rather than 5. Raid 5 just isn't that great for write performance.

>
>Aren't these results strange for what is said to be an "ideal cost-
>effective solution for applications where high levels of sustained
>read and write performance are required, including video streaming,
>web content, reference data and fixed content storage" ??
>
>What can I do?? I am writing an application that does video
>acquisition in real time...
>
>Thanks a lot,
>Marco
>



Fondazione Distrofici Onlus

2007-09-07, 7:15 am

On 6 Set, 17:53, w...@panix.com (the wharf rat) wrote:
> In article <1189011849.248202.309...@d55g2000hsg.googlegroups.com>,
> Fondazione Distrofici Onlus <i...@disys.it> wrote:


>
> 10MB/sec for random writes in a raid 5 doesn't sound that
> far off to me... The ideal situation is very large sequential writes.
> Check that you have the write cache enabled. Make sure that command queueing
> is enabled and not set to 1.
>
> If your application is very write intensive IMHO you should use
> RAID 10 rather than 5. Raid 5 just isn't that great for write performance.
>
>
>

Thank you very much for your answer!
I've just changed all my drives and now sequential writing for large
files is 90 MB/s.
In my opinion there's an incompatibility between Adaptec 2810SA and
Maxtor DiamonMax 21 320 GB hard disks.
But, please, tell me about "command queueing": where should I see that
configuration? In BIOS?
Thanks again, Marco.

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