Monday, February 15, 2016

zfs - NexentaStor: how to partition SSD disk?



I'm trying to set up some homegrown storage using a desktop motherboard, 4 x SATA drives and 2 x SSD drives.



I'd really like to use NexentaStor for its nice web interface and for it is some production-ready status, but I also want to use ZIL and L2ARC on my storage to speed things up.




I plan to partition both SSDs as 4 partitions (OS, swap, ZIL, L2ARC), put NexentaStor on mirror made of 1st partitions of each SSD, ZIL on mirror made of 3rd partitions, and added both 4th partitions as two L2ARC devices. Then I plan to create RAID-Z2 pool, add ZIL and 2 x L2ARC to it.



The problem is, NexentaStor won't partition and drive it uses. So I can't simply "break" SSDs for some partitions, I need to use the whole SSD drive for one purpose, which is not a good idea since SSD are too big for "just boot me up" usage.



So, the question is: are there any way I can setup NexentaStor with ZIL and L2ARC using 4 x SATA HDD and 2 x SSD?



P.S. I was successful to do the same setup under FreeBSD, so there is no any ZFS limitation on that (no wonder about).



P.P.S. I'm not sure but what if I use Solaris LiveCD to per-partition SSD and try to install Nexentra on it but if it is possible at all?


Answer




I'd suggest dedicated drives for OS and dedicated disks for data. NexentaStor is software RAID and the loss of an OS disk can be painful. You can combine L2ARC and ZIL, but the class of SSDs you're probably using won't be helpful as ZIL devices.



I understand the desire to try to use all of these ZFS features, but you really have to do it the right way. I run many ZFS systems without L2ARC because it's often not necessary for the application or I/O patterns. Try to maximize RAM first.



The partitioning of the SSDs for ZIL and ARC can be done from the command line using parted. You would also need to add them to the zpool via the CLI.


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