[CentOS] RAID 5 setup?

Chan Chung Hang Christopher christopher.chan at bradbury.edu.hk
Sat Mar 27 07:36:48 UTC 2010


Benjamin Franz wrote:
> Robert Heller wrote:
>> I suspect that this is a simular case to what I did: I have a server
>> with 4 drives.  I have several (small) RAID1 partitions (/boot, /,
>> /usr, /var, etc.) with 4 mirrors and one large RAID5 with three
>> partitions and a hot spare (a LVM volumn group, containing /home and
>> some other partitions). I would guess that the admin with the "8-way
>> RAID1 for the OS" probably also has a 6 or 8 disk RAID5 or RAID6 for
>> the bulk of the disks
> Yup. 8 way RAID1 for the OS, 8 way RAID6 for the data. I was hoping when 
> I setup the 8-way RAID1 for the OS that I would get really good read 
> speeds since md is supposed to stripe reads from RAID1, but in practice 
> the RAID6 completely kills it for read performance (~61 MB/sec from the 
> RAID1 partition vs ~200 MB/sec from the RAID6 partition).

What are you running? I think there was a patch that evened out the 
reads across all members as it would at times solely read from one and 
then another...


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