Data Storage - SATA Write Throughput

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Author SATA Write Throughput
nospam

2005-05-24, 5:53 pm

I've got an Adaptec Serial ATA RAID 21610SA Controller card with 6 pairs of
RAID1 disks attached. The card is rated at 1.5Gbps. Writing to one pair, I
get about 30MB/s. Writing to 2 pairs at the same time, I get a total of
40MB/s. I get 40MB/s when I right to 3,4,5, or 6 pairs at the same time.
It seems 40MB/s is the hard limit for this card. I was hoping to get
something close to 6*30MB/s = 180MB/s for the system. Any ideas?


flux

2005-05-25, 2:46 am

In article <6MIke.1$l1.0@dfw-service2.ext.ray.com>,
"nospam" <nospam@nospam.com> wrote:

> I've got an Adaptec Serial ATA RAID 21610SA Controller card with 6 pairs of
> RAID1 disks attached. The card is rated at 1.5Gbps. Writing to one pair, I
> get about 30MB/s. Writing to 2 pairs at the same time, I get a total of
> 40MB/s. I get 40MB/s when I right to 3,4,5, or 6 pairs at the same time.
> It seems 40MB/s is the hard limit for this card. I was hoping to get
> something close to 6*30MB/s = 180MB/s for the system. Any ideas?


Is the card PCI-X? Is it in a PCI-X slot? Does the card provide
individual channels for each drive? How fast is reading? Presumably,
RAID-1 will be slower writing than reading. How fast is the computer? If
you put this in a system with 256 MB of RAM, that will certainly impact
performance. Finally, how did you make these speed calculations?
Oracle

2005-05-28, 5:46 pm

What OS are you using? Have you explored filesystem block size? Depending on
the type of I/O and/or application its possible you are generating a lot of
I/O with too small a block size.


"nospam" <nospam@nospam.com> wrote in message
news:6MIke.1$l1.0@dfw-service2.ext.ray.com...
> I've got an Adaptec Serial ATA RAID 21610SA Controller card with 6 pairs
> of
> RAID1 disks attached. The card is rated at 1.5Gbps. Writing to one pair,
> I
> get about 30MB/s. Writing to 2 pairs at the same time, I get a total of
> 40MB/s. I get 40MB/s when I right to 3,4,5, or 6 pairs at the same time.
> It seems 40MB/s is the hard limit for this card. I was hoping to get
> something close to 6*30MB/s = 180MB/s for the system. Any ideas?
>
>



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