[Dovecot] OT - small hd recommendation

Patrick Domack patrickdk at patrickdk.com
Wed Aug 31 03:51:41 EEST 2011

SATA 1 vs SATA 3 won't change the seek performance of the drive,  
unless your stay fully within the drives cache.

Only 2 things affect how many iops you can get from a drive. The  
physical diameter and the speed. You can affect the physical diameter  
of the drive by selecting how much of the drive you use, like only  
using 200gigs out of a 500gig drive.

If you do opt for raid6, that would be a huge cpu overhead, and if you  
stick with 4 drives, not worth it, every write would hit atleast 3  
drives then, instead of just two they do currently, with no gain of  

Quoting "Daniel L. Miller" <dmiller at amfes.com>:

> A little OT - but I've seen a few opinions voiced here by various  
> admins and I'd like to benefit.
> Currently running a single combined server for multiple operations -  
> fileserver, mailserver, webserver, virtual server, and whatever else  
> pops up.  Current incarnation of the machine, after the last  
> rebuild, is an AMD Opteron 4180 with a Supermicro MB using ATI SB700  
> chipset - which means it supports SATA 3.0.
> Current storage is one o/s drive, and a 4-drive RAID10 array.  The  
> RAID10 is using the Linux softraid via mdadm.  The drives are  
> Seagates - ST3160811AS.  So it's 320GB of storage, and SATA 1.5.
> I'm seeing some warnings & errors in my logs & dmesg - and Google  
> tells me this can the result of several factors, including the hard  
> drives.  I haven't seen any SMART warnings as yet - but I am getting  
> a little nervous and thinking about upgrading the storage.
> At this time, I'm just interested in recommendations for hard drives  
> & partitioning strategy.  At the time I created the RAID10 array - I  
> was still in the early stages of learning these technologies (not  
> that I know that much more now!) so I probably didn't take advantage  
> of any of the advanced settings such as stripe size, cluster size,  
> etc.  I am using XFS.
> As part of the potential upgrade, I'm considering changing to RAID6  
> - seems a bit more efficient use of space.  I see no reason for SSD  
> - I think a set of reasonable 7200rpm drives should be just fine.   
> What I don't know is, compared to my current 4 drive RAID10 with  
> SATA 1.5, would even a single SATA 3 drive be comparable in terms of  
> seek performance?  Should I stick with the RAID-10?
> -- 
> Daniel

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