I''ve got a server at home that I''m about to set up. I''ll be moving 3x 500GB SATA disks into it from a different machine, so the config of those is set. What I need help with is the other disks. I''m not sure what the best way to use them is. I want to do ZFS Boot, so I''m limited to what config I can use for these other disks. I have 4x 73GB 15K rpm SAS disks. I''ll need to run at least two of them in a mirror for the OS. The question is, how do I use the other two? I''d like to at least use them for ZIL, and possibly L2ARC, but the question is this: Am I better off running drives 3 and 4 as a mirror for ZIL/L2ARC or am I better off using the SAS controller to create two stripes of two disks each and then use ZFS to mirror what''s left over, leaving space for ZIL/L2ARC. Thoughts? -brian -- "Coding in C is like sending a 3 year old to do groceries. You gotta tell them exactly what you want or you''ll end up with a cupboard full of pop tarts and pancake mix." -- IRC User (http://www.bash.org/?841435)
On Mon, Jan 12, 2009 at 3:23 PM, Brian Hechinger <wonko at 4amlunch.net> wrote:> I''ve got a server at home that I''m about to set up. I''ll be moving 3x 500GB SATA > disks into it from a different machine, so the config of those is set. What I need > help with is the other disks. I''m not sure what the best way to use them is. > > I want to do ZFS Boot, so I''m limited to what config I can use for these other disks. > > I have 4x 73GB 15K rpm SAS disks. I''ll need to run at least two of them in a mirror > for the OS. The question is, how do I use the other two? I''d like to at least use > them for ZIL, and possibly L2ARC, but the question is this: > > Am I better off running drives 3 and 4 as a mirror for ZIL/L2ARC or am I better off > using the SAS controller to create two stripes of two disks each and then use ZFS to > mirror what''s left over, leaving space for ZIL/L2ARC. > > Thoughts? > > -brianHi Brian, I tried running with one 146Gb 15k SAS disk for Zil and a 2nd (identical) disk for L2ARC and it turns out to be a "bad" use of that hardware. "Bad" is a highly subjective assessment, based on the type of workload you''re running and your expectations - but, for my money, those disks would be better utilized as another zfs mirror - or as members of a stipe as you''ve specified above. There is also the bug with removing the drives from the zpool if you change your mind (you can only remove the cache drive right now IIRC). IMHO it makes more sense to add RAM to the system (if possible) in order to get the best performance from ZFS - or wait until the price/performance of SSDs make them a compelling buy. Regards, -- Al Hopper Logical Approach Inc,Plano,TX al at logical-approach.com Voice: 972.379.2133 Timezone: US CDT OpenSolaris Governing Board (OGB) Member - Apr 2005 to Mar 2007 http://www.opensolaris.org/os/community/ogb/ogb_2005-2007/
On Mon, Jan 12, 2009 at 04:55:15PM -0600, Al Hopper wrote:> Hi Brian, > > I tried running with one 146Gb 15k SAS disk for Zil and a 2nd > (identical) disk for L2ARC and it turns out to be a "bad" use of that > hardware. "Bad" is a highly subjective assessment, based on the type > of workload you''re running and your expectations - but, for my money, > those disks would be better utilized as another zfs mirror - or as > members of a stipe as you''ve specified above. There is also the bug > with removing the drives from the zpool if you change your mind (you > can only remove the cache drive right now IIRC).Ok, so partitioning the OS install disk to leave some for the ZIL is still not a good idea? You can remove ZIL though, right?> IMHO it makes more sense to add RAM to the system (if possible) in > order to get the best performance from ZFS - or wait until the > price/performance of SSDs make them a compelling buy.Yeah, I can''t wait for SSDs that I can actually afford. :) -brian -- "Coding in C is like sending a 3 year old to do groceries. You gotta tell them exactly what you want or you''ll end up with a cupboard full of pop tarts and pancake mix." -- IRC User (http://www.bash.org/?841435)
> "Coding in C is like sending a 3 year old to do groceries. You gotta > tell them exactly what you want or you''ll end up with a cupboard full of > pop tarts and pancake mix." -- IRC User (http://www.bash.org/?841435)but who sends a baby to do groceries? can''t pick up the wine for daddy. and which C? ANSI C was so powerful; C++ was so easy; and I didn''t need to learn JAVA to use JAVA... just that my JAVA codes take more CPU juice to run, I don''t know why. sorry, I have to put down my chinese seafood delivery talking about C. cheers, z