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Old 04-11-2008, 01:43 AM
Jerry Geis
 
Default question on RAID performance

Hi all,

I was wonder what experiences there are out there with using RAID-X for
performance increases. I do use RAID-1 (2 disks) but am interested in
attemtps to gain higher R/W performance. Do the RAID-5's etc give
noticeable

performace increases?

A significant help for me was using ccache for compiling programs. That was
a real performance increase.

Thanks for any suggestions/opinions.

jerry
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Old 04-11-2008, 03:06 AM
"John J. Lee"
 
Default question on RAID performance

If you want to higher R/W performance, you should go for raid0.
raid0 fragments the data into the number of disks and distributes them.
It gains a big performance. One drive fails, however, all data gone.
raid5's benefit is not the speed but the effective space usage with
the least data redundancy.
Bitwise parity calculation consumes lots of processing power. So
raid5 is the least choice in terms of performance.

-john

On Thu, Apr 10, 2008 at 6:43 PM, Jerry Geis <geisj@pagestation.com> wrote:
> Hi all,
>
> I was wonder what experiences there are out there with using RAID-X for
> performance increases. I do use RAID-1 (2 disks) but am interested in
> attemtps to gain higher R/W performance. Do the RAID-5's etc give
> noticeable
> performace increases?
>
> A significant help for me was using ccache for compiling programs. That was
> a real performance increase.
>
> Thanks for any suggestions/opinions.
>
> jerry
> _______________________________________________
> CentOS mailing list
> CentOS@centos.org
> http://lists.centos.org/mailman/listinfo/centos
>



--
John Juyoung Lee
(510)486-7510 / jjlee@lbl.gov
(510)301-2315 / john.jy.lee@gmail.com
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Old 04-11-2008, 03:18 AM
"Miguel Medalha"
 
Default question on RAID performance

Have you tried RAID 10? It combines the security of RAID 1 with the speed of
RAID 0. dmraid supports this RAID type.



I was wonder what experiences there are out there with using RAID-X for
performance increases. I do use RAID-1 (2 disks) but am interested in
attemtps to gain higher R/W performance. Do the RAID-5's etc give
noticeable performace increases?


_______________________________________________
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CentOS@centos.org
http://lists.centos.org/mailman/listinfo/centos
 
Old 04-11-2008, 04:13 AM
Guy Boisvert
 
Default question on RAID performance

John J. Lee wrote:

On Thu, Apr 10, 2008 at 6:43 PM, Jerry Geis <geisj@pagestation.com> wrote:

Hi all,

I was wonder what experiences there are out there with using RAID-X for
performance increases. I do use RAID-1 (2 disks) but am interested in
attemtps to gain higher R/W performance. Do the RAID-5's etc give
noticeable
performace increases?

A significant help for me was using ccache for compiling programs. That was
a real performance increase.

Thanks for any suggestions/opinions.

jerry

>
>
> If you want to higher R/W performance, you should go for raid0.
> raid0 fragments the data into the number of disks and distributes them.
> It gains a big performance. One drive fails, however, all data gone.
> raid5's benefit is not the speed but the effective space usage with
> the least data redundancy.
> Bitwise parity calculation consumes lots of processing power. So
> raid5 is the least choice in terms of performance.
>
> -john
>


I had about the same interrogation a couple of months ago. I had to
upgrade a mail server that was using a single IDE drive to store about
90 Gigs of mail, served by Communigate Pro on CentOS 4.6 (32 bits). The
server was starting to crawl with high %iowait. The drive was simply a
regular Western-Digital 7200 RPM 200 Gigs drives. Imagine the random
access load, which is simply too much for a drive which is designed to
handle single user load.


I finally set for 4 x Seagate SAS 73 Gigs 15000 RPM on RAID 10. The
performance is very good. About 150-160 MiB/s througput R/W. We use an
Adaptec 3405 (Unified SAS/SATA Crontroller, CentOS stock drivers) on a
new Tyan Transport TA26 (B3992-E), 4 Gig RAM, Opteron 2214 & CentOS 5
x86_64.


I made tests with the same server in RAID 5. Read throughput was about
the same but write was slightly lower (XOR Calculation) at about 135
MiB/s which is still real good. I chose RAID 10 because i had enough
space with 146 Gigs RAID 10 and i wanted absolute throughput for our 50
e-mail users which use Outlook with Communigate MAPI Plugin. Sometimes
they click on a big public sub-directory and sync between Outlook and
the server takes place (local caching). The user are very satisfied and
CentOS 5 is rock solid, providing a very good service since 2 months.
The previous server run for about 3 years without any problem, providing
excellent service even if it was running on modest hardware: Athlon XP
2500, Asus A7V600, 1 Gig RAM.


On another little project (friend's media file server), i assembled a
cheap server with Asus M2N-e, Athlon Dual Core 4600+, 1 Gig DDR2 667 RAM
, 40 Gigs IDE system drive and 4 x Western-Digital 500 Gigs RAID Editon
(7200 RPM) data array. I used CentOS 5 x86_64 software RAID 5 (4 x 500
Gigs) and managed to get 35-40 MiB/s write throughput, which was much
more than what he got using Intel ICH-8 RAID 5 on his Windoze PC (same
drives). The Athlon DC 4600 handles the XOR very easily (low cpu usage)
and the bottleneck seems to be on the bus (Regular PCI bus, 132 MiB/s
max combined). He's absolutely satisfied with his new CentOS 5 Samba
server. Combine that with WebMIN and a couple of scripts, he's stunned
by how it's easy to use his server! I still wonder how people are
paying for Winblows Home server...



Hope this helped a bit!


Guy Boisvert, ing.
IngTegration inc.
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Old 04-11-2008, 04:34 AM
"John J. Lee"
 
Default question on RAID performance

I am currently running 7 raid10 data servers. I can say read speed
increases but I doubt the write speed comparing to non raid setup.
The main advantage of the raid is redundancy but not
the performance. If you want to boost the disk performance, go for
the faster drive with more than
10,000rpm spinning speed.

-john

On Thu, Apr 10, 2008 at 8:18 PM, Miguel Medalha <miguelmedalha@sapo.pt> wrote:
> Have you tried RAID 10? It combines the security of RAID 1 with the speed of
> RAID 0. dmraid supports this RAID type.
>
>
>
> > I was wonder what experiences there are out there with using RAID-X for
> > performance increases. I do use RAID-1 (2 disks) but am interested in
> > attemtps to gain higher R/W performance. Do the RAID-5's etc give
> noticeable performace increases?
> >
>
>
> _______________________________________________
> CentOS mailing list
> CentOS@centos.org
> http://lists.centos.org/mailman/listinfo/centos
>



--
John Juyoung Lee
(510)486-7510 / jjlee@lbl.gov
(510)301-2315 / john.jy.lee@gmail.com
_______________________________________________
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http://lists.centos.org/mailman/listinfo/centos
 
Old 04-11-2008, 01:34 PM
Jason
 
Default question on RAID performance

while it takes a minimum of 6 disks, we've had great luck with RAID 50.
Two separate RAID 5 arrays (fast read, moderate writes) that are then
placed into a RAID 0 (fast read, fast write). you lose 2 drives worth of
space, but lord it's fast and the data is mirrored. Not sure if you can
do the whole thing in software. I use two 3Ware 9650SE cards to do the
RAID 5 and I do RAID 0 in software.


Jason
www.cyborgworkshop.org


John J. Lee wrote:
> I am currently running 7 raid10 data servers. I can say read speed
> increases but I doubt the write speed comparing to non raid setup.
> The main advantage of the raid is redundancy but not
> the performance. If you want to boost the disk performance, go for
> the faster drive with more than
> 10,000rpm spinning speed.
>
> -john
>
> On Thu, Apr 10, 2008 at 8:18 PM, Miguel Medalha <miguelmedalha@sapo.pt> wrote:
>> Have you tried RAID 10? It combines the security of RAID 1 with the speed of
>> RAID 0. dmraid supports this RAID type.
>>
>>
>>
>>> I was wonder what experiences there are out there with using RAID-X for
>>> performance increases. I do use RAID-1 (2 disks) but am interested in
>>> attemtps to gain higher R/W performance. Do the RAID-5's etc give
>> noticeable performace increases?
>>
>> _______________________________________________
>> CentOS mailing list
>> CentOS@centos.org
>> http://lists.centos.org/mailman/listinfo/centos
>>
>
>
>
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Old 04-11-2008, 01:57 PM
"Ross S. W. Walker"
 
Default question on RAID performance

Jason wrote:
> John J. Lee wrote:
> > On Thu, Apr 10, 2008 at 8:18 PM, Miguel Medalha <miguelmedalha@sapo.pt> wrote:
> >>>
> >>> I was wonder what experiences there are out there with using RAID-X for
> >>> performance increases. I do use RAID-1 (2 disks) but am interested in
> >>> attemtps to gain higher R/W performance. Do the RAID-5's etc give
> >>> noticeable performace increases?
> >>
> >> Have you tried RAID 10? It combines the security of RAID 1 with the speed of
> >> RAID 0. dmraid supports this RAID type.
> >>
> >
> > I am currently running 7 raid10 data servers. I can say read speed
> > increases but I doubt the write speed comparing to non raid setup.
> > The main advantage of the raid is redundancy but not
> > the performance. If you want to boost the disk performance, go for
> > the faster drive with more than
> > 10,000rpm spinning speed.
> >
> > -john
> >
>
> while it takes a minimum of 6 disks, we've had great luck with RAID 50.
> Two separate RAID 5 arrays (fast read, moderate writes) that are then
> placed into a RAID 0 (fast read, fast write). you lose 2 drives worth of
> space, but lord it's fast and the data is mirrored. Not sure if you can
> do the whole thing in software. I use two 3Ware 9650SE cards to do the
> RAID 5 and I do RAID 0 in software.

The choice of a RAID setup really depends on the application it is
used for and a RAID 50 or RAID 6 may be fast for a file server it
will perform poorly for a database, mail or virtual machine server.

If your application is database, mail or virtualization guests then
the way to go is RAID10.

The type of disk is important too. If you are doing file services
on RAID5/50/6 then you may as well stick with SATA, but if you
are doing database or mail then a SAS 10K drive may be in order
depending on the amount of transactions or virtual machines,
their type and applications they are running.

There is no one solution fits all unless you have the kind of money
to buy SAS 10K RAID10s on hardware RAID with BBU write cache for
everything.

Tell us what the application and hardware is, the number of clients,
VMs or transactions/mails you plan on it handling and a best-cost
solution can be provided.

BTW RAID50 can be done by adding 2 RAID5 PVs to a LVM VG and
creating striped LVs across them. All by software.

-Ross

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