[Gluster-users] Advice for setup: SW RAID 6 vs JBOD

[Strahil Nikolov]

 >What I do have is an extra SSD disk per server which I plan to use as LVM cache for the bricks (Maybe just 1 disk, maybe 2 >with SW RAID 1). I still need to test how LVM / gluster are going to handle the failure of the cache disk.
 
Are you planing to use LVM cache for reads (writethrough) only or both read + writes (writeback) ? 
If you pick the writeback - which means that you first write to the SSDs and only then push the data to the slow HDDs , then you need a raid1 for the SSD-based LVM cache , or a pure replica3 cause if you loose 1 SSD - the whole brick is down and you need to sync from scratch - and with the size of data you have - this will not be so nice.
Note: Don't forget that thin LVM is the only way that gluster can use snapshots.
Best Regards,Strahil Nikolov  
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