sas 15000rpm vs raid0 6hdd sas 7200rpm

[ndhuy]

I'm looking for a benchmark of single sas 15000rpm vs raid0 6hdd sas 7200rpm
I'm using webserver . I thinks single win raid because raid is effective with file > 16KB , but most file is < 4KB and there are many files loaded in a conection


sory for my bad english , i am vietnamese

 

[typo3usa]

im sorry - but I am not sure what you are asking.

Are you asking if you should use SAS 15K RPM drives vs. SATA 7200RPM drives ?

the SAS will of course give you a much better performance - as they are literally twice the speed.

Generally SAS however are also much smaller and more expensive.

One alternative would be to use SAS to place MySQL instances onto - and let the rest run on SATA

there are a number of benchmarking tools - but to be able to help more - what RAID card (if any) are you looking to use?

Also- Raid0 vs. Raid 10 vs. Raid 1 ?
Just wondering as Raid0 will pretty much give you one huge disk - but the striping should one drive ever fail - would literally just kill all your data.

Raid 5 is not a good option imho - simply because of how Raid5 operates -


RAID 5 is a dirty word in the DBA community and beyond. There are websites devoted to trash RAID 5. - while Raid 10 does not have the highest speed like Raid5 (and its very very close btw) - Raid 10 seems to be a much better choice...

Hope that helps

 

[dietmar]

while Raid 10 does not have the highest speed like Raid5 (and its very very close btw) - Raid 10 seems to be a much better choice...

RAID 10 is usually much faster than RAID 5 (or can you point me to some benchmarks showing the opposite?)

 

[ndhuy]

sory , but my problem is single sas vs raid0 sata in a web server

 

[typo3usa]

I would forgo raid and go with the 2 SATA drive
interesting they cannot give raid 1 but can give raid 0 ?
where are you buying this ?

If you went w/o raid - then you could at least run scripts to mount that second drive - do backups to it and then umount it until its needed -

that would help keep hackers at bay a little - most wont look to mount what is not mounted...

in regards to Raid 10vs Raid 5 - Technically Raid 5 should be slower -
just i guess depends on what I have seen - but then again not comparing all the same controllers together either...
Adaptec vs 3Ware - some with 128mb others with 1024mb / 1GB ram etc

your right when it comes to Raid 10 however ..

Just for the sake of comparison, let’s say we had 8 drives - doing a database.

For this database - that it is 100% reads and 100% random. The end result is that all eight of the drives will see a command, or an IO. That means that if each drive can do 100 IOs per second, then the RAID-10 can do 800 IOPS total.

On a RAID-5 with 100% reads there are no RAID-5 calculations other than the block redirection due to the striping, which is almost identical to the redirection in RAID-10.



So the end result is that all eight drives are used (since parity is distributed across all drives), and therefore RAID-5 will do the same 800 IOPS as RAID-10.


The issue comes into play when you start doing writes... vs reads.



In a Raid 10 array - each will be written to 2 drives - so of course - the performance would drop to 1/2 (in the case of the reads @ 800 IOPS - writes would be 400IOPS)



Raid 5 however - since host access is done to 4 IOs - - since there are two reads and two writes - the performance is literally one Quarter that of the read - or in the case of this example - 200IOPS



more info is here: http://www.cyberciti.biz/tips/raid5-vs-raid-10-safety-performance.html



if that helps



this is what I get for jumping in @ 1:30AM :-/



so yeah - Raid 10 is better for performance

 

[ndhuy]

you forgot one thing : my server is web server . Amount of file in a conection is very large , so raid is useless

 

[Onyx]

Also don't forget the number of spindles. A raid5 with 16 disks and a decent controller will be way faster than a raid10 with 4 disks.

I think that was the original quesion: What is the fastest: A single sas 15000rmp disk or a raid0 array of 6 7200rpm disks.
I would think raid0 array.

 

[ndhuy]

But my server is web server not file system server which size of every file is < 1 KB , so only one HDD service for all , raid is uneffect except it's cache

When everybody in forum is sleeping , i'm posting .

 

[typo3usa]

a flat webserver yes
but - will this have any databases ?

for example - what control panel if any are you using?

cPanel will install mysql , as would Plesk - and some others
Are you planning on having a 2nd server for SQL instances?

We run a large web server farm -
and virtually the entire farm (in 2 data centers) run on proxmox now.

A Server running Raid 0 is just an accident waiting to happen in the hosting industry without a good backup and hot-swap live plan.

Here are my simple thoughts for you.

1. Decide the balance needed between Speed and Data Integrity.
2. If going for Speed - look @ a second system to do backups - - We use www.R1soft.com for our backups - however not sure if you can spend that cash or not...

If it were me - I would be looking into the Dell Outlet if money was tight - grab a 2950 or similar - and build my own system up to have the best of both worlds- Raid and Speed...