raidz plus mirror on the same disk different slice in 2 pools

Question

I need a little assistance. I have 6 2TB disks. I'm planning to assign approximately 500GB to my root pool slice 0 mirrored with another disk, since one disk isn't used up I then decided to do a raidz pool with 5 of the disks including the left over space from 2 disk that has root pool but with different slice.

for example:

root pool
    disk0 slice 0
    mirror disk 1 slice 0

mypool
    raidz
        disk 0 slice 7
        disk 1 slice 7
        disk 2 slice 0
        disk 3 slice 0
        disk 4 slice 0

disk 5 for hot spare.

I'm not sure is it recommended to do so and would like to know if anyone have any idea if the entire disk 1 fails, how does it recover? how does the system handle such failure under such config ?

Please provide the output of `zpool status` – longneck Jan 29 '13 at 15:12 — longneck, Jan 29 '13 at 15:12
http://imageshack.us/photo/my-images/802/zpool.jpg/ – user156594 Jan 29 '13 at 15:27 — user156594, Jan 29 '13 at 15:27

ewwhite · Accepted Answer · 2013-01-29T15:34:01.383

0

That's a messy configuration. It can work, though.

Root does not need much space. Is there any chance you could use a smaller pair of disks (or a single SSD) to use as root to simplify the entire setup?

edited Jan 29 '13 at 15:34

answered Jan 29 '13 at 14:45

ewwhite

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nope...if this configuration is messy then I might just do it 2 disks per pool...or is there any better recommended config with 6 disks? – user156594 Jan 29 '13 at 15:22
1

this configuration will limit the usable space of your `mypool` pool to 1.5 TB * (5 - 1). you're effectively wasting 500 gb of disk 2, 3 and 4. – longneck Jan 29 '13 at 15:32
@longneck can you suggest a more practical method configuring this? – user156594 Jan 29 '13 at 15:36
*"use a smaller pair of disks (or a single SSD) to use as root"* – ewwhite Jan 29 '13 at 15:46
It depends. If you are OK with limiting your storage and extra disks are out of the question, then this configuration is about as good as you can get. Not knowing Solaris but extrapolating my FreeBSD knowledge, you could create a very small `/boot` partition (1GB) and put your OS in the raidz volume, too. That would allow you to use the full capacity of all of your drives. – longneck Jan 29 '13 at 15:51
ewwhite thx for the advice =) @longneck if that's the case then i will try 2disks per pool mirrored, thx =) – user156594 Jan 29 '13 at 15:59
@longneck oh...I misunderstood you, I thought that you recommended for mirroring in pairs. I'm not sure about FreeBSD, but in solaris 10 root partition is recommended to use the entire disk mirrored, meaning the root pool can't be in raidz. assuming that raidz1 minimum requirement is 3 disks, how about I mirror the root pool with a disk and 3 for raidz1 pool the extra one will be for hot spare? paranoid? – user156594 Jan 29 '13 at 18:05
I'm not recommending one particular configuration over another for your implementation. I don't know your requirements. That's for you to decide. I was just pointing out that 1) your configuration is slightly odd and wastes a good chunk of space on most of your drives, and 2) that you could use a /boot pool to maximize your available space. Ultimately, only you know your requirements and can decide what is best for your application. – longneck Jan 29 '13 at 19:52

score 0 · Answer 2 · answered Feb 04 '13 at 23:57

You'd get a better overall result if you used 2 disks to mirror the rpool and use the other 4 disks in a 1+0 setup for mypool (two mirrors of two disks). This way you get a total of 6TB of storage, you're resilient to the failure of any one disk and there's minimal waste. Your write performance may not be quite as good I suppose.

raidz plus mirror on the same disk different slice in 2 pools

2 Answers2