60GB SSD drives using the SF 1222 controller can be had now for around $100. I know ZFS likes to use the entire disk to do it''s magic, but under X86, is the entire disk the entire disk, or is it one physical X86 partition? In the past I have created 2 partitions with FDISK, but format will only show one of them? Did I do something wrong, or is that the way it works? So, maybe what I want to do won''t work....But this is my thought.... on a single 60GB SSD drive, use FDISK to create 3 physical partitions, a 20GB for boot, a 30GB for L2ARC and a 10GB for ZIL? Or is 3 physical Solaris partitions on a disk not considered the entire disk as far as ZFS is concerned? Can a ZIL and/or L2ARC be shared amongst 1+ ZPOOLs, or must each pool have it''s own? If each pool must have it''s own, can a disk be partitioned so a single fast SSD can be shared amongst 1+ pools? Thanks -- This message posted from opensolaris.org
> From: zfs-discuss-bounces at opensolaris.org [mailto:zfs-discuss- > bounces at opensolaris.org] On Behalf Of Bill Werner > > on a single 60GB SSD drive, use FDISK to create 3 physical partitions, a20GB> for boot, a 30GB for L2ARC and a 10GB for ZIL? Or is 3 physical Solaris > partitions on a disk not considered the entire disk as far as ZFS isconcerned? You can do that. Other people have before. But IMHO, it demonstrates a faulty way of thinking. "SSD''s are big and cheap now, so I can buy one of these high performance things, and slice it up!" In all honesty, GB availability is not your limiting factor. Speed is your limiting factor. That''s the whole point of buying the thing in the first place. If you have 3 SSD''s, they''re each able to talk 3Gbit/sec at the same time. But if you buy one SSD which is 3x larger, you save money but you get 1/3 the speed. Whether you are using multiple HDD''s or multiple SSD''s, you''re probably doing it because you want size, speed, and reliability better than a single disk. You''re defeating all of these purposes by trying to leverage a single disk for your OS, l2arc, and log devices simultaneously. That''s not to say there''s never a situation where it makes sense. Other people have done it, and maybe it makes sense for you. But probably not.
Understood Edward, and if this was a production data center, I wouldn''t be doing it this way. This is for my home lab, so spending hundreds of dollars on SSD devices isn''t practical. Can several datasets share a single ZIL and a single L2ARC, or much must each dataset have their own? -- This message posted from opensolaris.org
On Wed, Dec 22, 2010 at 9:27 PM, Bill Werner <werner at cubbyhole.com> wrote:> on a single 60GB SSD drive, use FDISK to create 3 physical partitions, a 20GB for boot, a 30GB for L2ARC and a 10GB for ZIL? ? Or is 3 physical Solaris partitions on a disk not considered the entire disk as far as ZFS is concerned?Solaris is not happy using partitions and slices at the same time. You can do it, but I don''t think it''s recommended. Creating multiple slices on the install drive isn''t supported by the installer, or it wasn''t the last time I did a clean build. A word of caution: I burned out a 30GB SSD (OCZ Vertex, which has an Indilinx Barefoot) in about 3 months using it as the L2ARC for my home media server. I''m not sure if the write cycles were used up, or if it was another problem, but it died and had to be RMA''d. I suspect that writing new media and viewing habits resulted in a lot of cache churn. -B -- Brandon High : bhigh at freaks.com
On 12/25/10 19:32, Bill Werner wrote:> Understood Edward, and if this was a production data center, I wouldn''t be doing it this way. This is for my home lab, so spending hundreds of dollars on SSD devices isn''t practical. > > Can several datasets share a single ZIL and a single L2ARC, or much must each dataset have their own? >The ZIL and L2ARC devices are per pool and thus shared shared amongst all datasets.
On Thu, December 23, 2010 22:45, Edward Ned Harvey wrote:>> From: zfs-discuss-bounces at opensolaris.org [mailto:zfs-discuss- >> bounces at opensolaris.org] On Behalf Of Bill Werner >> >> on a single 60GB SSD drive, use FDISK to create 3 physical partitions, a > 20GB >> for boot, a 30GB for L2ARC and a 10GB for ZIL? Or is 3 physical >> Solaris >> partitions on a disk not considered the entire disk as far as ZFS is >> concerned? > > You can do that. Other people have before. But IMHO, it demonstrates a > faulty way of thinking. > > "SSD''s are big and cheap now, so I can buy one of these high performance > things, and slice it up!" In all honesty, GB availability is not your > limiting factor. Speed is your limiting factor. That''s the whole point > of > buying the thing in the first place. If you have 3 SSD''s, they''re each > able > to talk 3Gbit/sec at the same time. But if you buy one SSD which is 3x > larger, you save money but you get 1/3 the speed.Boot, at least, largely doesn''t overlap with any significant traffic to ZIL, for example. And where I come from, even at work, money doesn''t grow on trees. Sure, three separate SSDs will clearly perform better. They will also cost 3x as much. (Or more, if you don''t have three free bays and controller ports.) The question we often have to address is, "what''s the biggest performance increase we can get for $500". I considered multiple rotating disks vs. one SSD for that reason, for example. Yeah, anybody quibbling about $500 isn''t building top-performance enterprise-grade storage. We do know this. It''s still where a whole lot of us live -- especially those running a home NAS.> That''s not to say there''s never a situation where it makes sense. Other > people have done it, and maybe it makes sense for you. But probably not.Yeah, okay, maybe we''re not completely disagreeing. -- David Dyer-Bennet, dd-b at dd-b.net; http://dd-b.net/ Snapshots: http://dd-b.net/dd-b/SnapshotAlbum/data/ Photos: http://dd-b.net/photography/gallery/ Dragaera: http://dragaera.info