[CentOS] Need advice on storage

Tue Nov 13 03:30:18 UTC 2007
redhat at mckerrs.net <redhat at mckerrs.net>

----- Original Message ----- 
From: "boisvert guy" <boisvert.guy at videotron.ca> 
To: "CentOS mailing list" <centos at centos.org> 
Sent: Tuesday, November 13, 2007 1:01:32 PM (GMT+1000) Australia/Brisbane 
Subject: Re : Re: [CentOS] Need advice on storage 

----- Message d'origine ----- 
De: "redhat at mckerrs.net" <redhat at mckerrs.net> 
Date: Lundi, Novembre 12, 2007 9:25 pm 
Objet: Re: [CentOS] Need advice on storage 
À: CentOS mailing list <centos at centos.org> 
> Guy, 
> I don't think raptor hard drives are necessarily value for money 
> and in your case, I believe that you'd be *much* better served 
> with some sort of redundancy and not just plain old striping. 
> I'd recommend that you stick with software raid and do something 
> like this; 
> 1 x silicon image PCI 4 port sata controller *not hardware raid* 
> ($25 from ebay for example) 
> 3 x 320gb sata hdd (~ $100 each here in Australia) 
> for a total of $325 AUD you'd get around 640gb or redundant 
> storage. 
> 2 x 74gb raptors will cost you $400 here in Australia ..... so 
> thats $75 *more* for almost 400gb *less* storage that is *not* 
> redundant ! 
> Linux software raid-5 performance is pretty good, my 4 x 400gb 
> sata's show 155mb/s reads with 'hdparm -t'. 
> No brainer ! 
> Cheers, 
> Brian. 

Hi Brian, 

Thanks for your response. I didn't say it but i can't go more than 2 drives (no more space in the case) and i backup the entire "mail drive" on a LVM backup array of 1.2 TB (3 drives) that serves to backup a windows file server too (Backup Array is 3 drives). It's not a perfect solution but it cames like it is because the Linux server took more and more job over the years. The Windoze servers do file serving + AD and Terminal Server. They have both server grade hardware but this little CentOS 4.5 server running on cheap hardware does almost all the job! 

As for RAID 5, with the *poor* CPU i have (Athlon 2500+), i'd be curious how fast it could write with multiples "streams" (server supports 45 WS). Don't get me wrong, i'm not saying that what you said is not right nor this isn't a good idea! 

I'm waiting a budget to change the server but it seems that for now, i have to search a temporary solution that could provide the most speed for the money and taking into account i'm dealing with low end mainboard / cpu. 

The next server should be something like the Tyan Transport TA26 (though doesn't seem to have redundant PS) with something like an Adaptec 3085 and SAS 15K Drives. 

Thanks again for your input! 

Guy Boisvert 

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how many drives can the server take ? and how many are there in it just now ? 

I'd even go as far as to say install the OS and the data on the 3 x 320gb sata drives and ditch the 80gb IDE. That is what I do and it is one of the strengths of software raid, the fact that you can mix and match raid types on the same physical disks. I'd go for a triple mirror for /boot and install the rest of the OS on the RAID-5 set or along with the data (grub can't boot of raid-5 as far as I'm aware). 

Alternatively if re-installing or copying your current OS onto new drives is not practical at this point I'd get 2 x 320g drives mirror them and also get that extra 1gb of RAM. The extra RAM could make more of a difference than 10k rpm drives. I dont think that you'll get anywhere near the performance you'd expect from a stripe compared to a mirror. As mentioned earlier, Raptors, IMO, are overrated and they are way hotter and noisier due to their higher spindle speed. 

How is the box performing ? what are you noticing when it is slow ? Wait IO ? Can you determine if it is IO bound or CPU bound ? 



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