[mirror-admin] Breaking the 1TB limit?

[Francois Petillon]

[sry for the delay, I have been off]
Chuck Anderson wrote:
> Money is tight right now for upgrading to larger/more storage.  Anyone 
> here play with cheap 1-2TB SATA disks + 3ware RAID cards for their 
> mirror?  What do you use for external enclosures?  Is this really a 
> viable option from a performance and reliability standpoint?

We do. On the servers I manage, I never use any stripping RAID (which 
exclude RAID0/4/5/6/10) unless we may set huge strip size (which may be 
the case sometime for RAID10 with 1 MB strip size). At the same time, 
daemons are patched (for mirrors, it is vsftpd & lighhtpd) to support 
bigger IOs (typically 1 MB using either madvise or fadvise).

In this case (bigger IOs with no fragmentation dued to RAID), we may get 
quite decent bandwidth from SATA disks.

On the specific case of the mirrors server, disks are setup as singles 
on the RAID controller and then setup on the system to be RAID1 array. 
This may look weird but the controller only allows two-disks RAID1 while 
you may have more disks on software RAID1. This allows us to scale by 
adding disks to the RAID1 array (which never occured since we support 
bigger IOs)

François

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