[CentOS] Infrastructure HELP!

Ryan Wagoner rswagoner at gmail.com
Fri Oct 30 00:28:17 UTC 2009


Looks like the price has gone up with the economy starting to recover.
I paid $68 per WD RE3 500GB drive on Amazon.com back in June.

I would still recommend going with 4 drives in RAID 10 over 2 in RAID
1 or even 3 drives in RAID 5. You will get almost double the
performance due to being able to stripe across the drives. RAID 1 is
just a mirror so you are only going to see the performance of a single
drive.

I have experience with software RAID levels 1 and 5 with mdadm. My
file server has a RAID 1 of 2 x 160GB Seagate SATA Drives and a RAID 5
of 3 x 1TB Hitachi SATA drives. For the RAID 1 drives hdparm shows
approx 68MB/s for each drive and 68MB/s for the array. With the RAID 5
I am seeing 82 MB/s for the drive and 140MB/s for the array. Keep in
mind this is an older Pentium D with the drives connected to an
Supermicro LSI 1068 SAS controller.

My ESXi box has a RAID 10 of 4 x 500GB Western Digital RE3 drives on a
PERC 6/i controller. The PERC is a Dell branded LSI controller. Inside
the virtual machines I am getting 148MB/s. Unfortunately I can't test
this at the ESXi level, but the MB/s will defiantly be higher as the
virtual machine has another layer to go through.

Ryan

On Thu, Oct 29, 2009 at 3:25 PM, ML <mailinglists at mailnewsrss.com> wrote:
> Ryan,
>
>> If you want performance stick with RAID 10. In general the more drives
>> (spindles) the faster the array. The Western Digital RE3 500 GB drives
>> are a good deal. You should be able to get 4 of those in the low
>> $200s. In RAID 10 this would give you better performance than 2 x 1TB
>> in RAID 1.
>>
> They are like $89.99 a  piece on NewEgg. I have a friend that has 1 x
> 1TB Seagate Raid level drives he will sell me for $100 each.
>
> Is software RAID 10 decent performance?
>
> -Jason
>
>> Ryan
>>
>> On Thu, Oct 29, 2009 at 2:36 PM, ML <mailinglists at mailnewsrss.com>
>> wrote:
>>>
>>> On Oct 29, 2009, at 11:11 AM, Neil Aggarwal wrote:
>>>
>>>> RAID 10 is striping across mirrored drives.
>>>>
>>>> So, if you have 4 x 1TB drives, think of it as two separate
>>>> 1 TB volumes.  The system will write half your data to
>>>> volume A and the other half to volume B.  The data in volume
>>>> A and B do not overlap.
>>>>
>>>> Now, each volume is composed of a mirrored set of drives.
>>>> Anything written to volume A is actually stored on two drives.
>>>> Anything written to volume B is actually stores on the other two
>>>> drives.
>>>>
>>>> Does this make sense?
>>>> Let me know if you need any more explanation.
>>>
>>> No it makes sense.
>>>
>>> I am contemplating if I really need 4 x 1tb in this system. I mean
>>> how
>>> much space with some photo's, web pages and MySQL take up if there
>>> are
>>> 5,000 subscribers to start up?
>>>
>>> Would 2 x 1TB enterprise drives be enough mirrored?
>>>
>>>> Also, when you move to a hosted solution, I would appreciate
>>>> your considering my company for it.
>>>
>>> Sure, I will be doing a lot of research on that for sure.
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