Re: [zfs-discuss] Re: ZFS/UFS layout for 4 disk servers
Manoj Joseph writes: Matt B wrote: Any thoughts on the best practice points I am raising? It disturbs me that it would make a statement like don't use slices for production. ZFS turns on write cache on the disk if you give it the entire disk to manage. It is good for performance. So, you should use whole disks when ever possible. Just a small clarification to state that the extra performance that comes from having the write cache on applies mostly to disks that do not have other means of command concurrency (NCQ, CTQ). With NCQ/CTQ, the write cache setting should not matter much to ZFS performance. -r Slices work too, but write cache for the disk will not be turned on by zfs. Cheers Manoj ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re[2]: [zfs-discuss] writes lost with zfs !
Hello Manoj, Thursday, March 8, 2007, 7:10:57 AM, you wrote: MJ Ayaz Anjum wrote: 2. with zfs mounted on one cluster node, i created a file and keeps it updating every second, then i removed the fc cable, the writes are still continuing to the file system, after 10 seconds i have put back the fc cable and my writes continues, no failover of zfs happens. seems that all IO are going to some cache. Any suggestions on whts going wrong over here and whts the solution to this. MJ I don't know for sure. But my guess is, if you do a fsync after the MJ writes and wait for the fsync to complete, then you might get some MJ action. fsync should fail. zfs could panic the node. If it does, you MJ will see a failover. Exactly. Files must be open with O_DSYNC of fdsync should be used. If you don't then writes are expected to be buffered and later put to disks which in your case has to fail. If you want to guarantee that when your applications writes something it's on stable storage then use proper semantics like shown above. -- Best regards, Robertmailto:[EMAIL PROTECTED] http://milek.blogspot.com ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Re: ZFS/UFS layout for 4 disk servers
Hello Matt, Wednesday, March 7, 2007, 7:31:14 PM, you wrote: MB So it sounds like the consensus is that I should not worry about using slices with ZFS MB and the swap best practice doesn't really apply to my situation of a 4 disk x4200. MB So in summary(please confirm) this is what we are saying is a MB safe bet for using in a highly available production environment? MB With 4x73 gig disks yielding 70GB each: MB 5GB for root which is UFS and mirrored 4 ways using SVM. MB 8GB for swap which is raw and mirrored across first two disks MB (optional: or no liveupgrade and 4 way mirror this swap partition) MB 8GB for LiveUpgrade which is mirrored across the third and fourth two disks MB This leaves 57GB of free space on each of the 4 disks in slices MB One zfs pool will be created containing the 4 slices MB the first two slices will be used in a zmirror yielding 57GB MB The last two slices will be used in a zmirror yielding 57GB MB Then a zstripe (raid0) will be layed over the two zmirrors MB yielding 114GB usable space while able to sustain any 2 drives failing without a loss in data Eventually if you care about how much storage is available then: 1. 8GB on two disks for / in mirrored config (SVM) 2. 8GB on another two disks for SWAP in mirrored config (SVM) 3. the rest of the disks for zfs a. raidz2 4 slices, capacity of 2x slice, bad random read performance b. raid-10 4 slices, capacity of 2x slice, good read performance, less reliability than a. You loose ability to do LU, but you gain some storage. -- Best regards, Robertmailto:[EMAIL PROTECTED] http://milek.blogspot.com ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: Re[2]: [zfs-discuss] writes lost with zfs !
robert, this applies only if you have full control on the application forsure ..but how do you do it if you don't own the application ... can you mount zfs with forcedirectio flag ? selim On 3/8/07, Robert Milkowski [EMAIL PROTECTED] wrote: Hello Manoj, Thursday, March 8, 2007, 7:10:57 AM, you wrote: MJ Ayaz Anjum wrote: 2. with zfs mounted on one cluster node, i created a file and keeps it updating every second, then i removed the fc cable, the writes are still continuing to the file system, after 10 seconds i have put back the fc cable and my writes continues, no failover of zfs happens. seems that all IO are going to some cache. Any suggestions on whts going wrong over here and whts the solution to this. MJ I don't know for sure. But my guess is, if you do a fsync after the MJ writes and wait for the fsync to complete, then you might get some MJ action. fsync should fail. zfs could panic the node. If it does, you MJ will see a failover. Exactly. Files must be open with O_DSYNC of fdsync should be used. If you don't then writes are expected to be buffered and later put to disks which in your case has to fail. If you want to guarantee that when your applications writes something it's on stable storage then use proper semantics like shown above. -- Best regards, Robertmailto:[EMAIL PROTECTED] http://milek.blogspot.com ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re[4]: [zfs-discuss] writes lost with zfs !
Hello Selim, Thursday, March 8, 2007, 8:08:50 PM, you wrote: SD robert, SD this applies only if you have full control on the application forsure SD ..but how do you do it if you don't own the application ... can you SD mount zfs with forcedirectio flag ? No -- Best regards, Robertmailto:[EMAIL PROTECTED] http://milek.blogspot.com ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: Re[2]: [zfs-discuss] writes lost with zfs !
Le 8 mars 07 à 20:08, Selim Daoud a écrit : robert, this applies only if you have full control on the application forsure ..but how do you do it if you don't own the application ... can you mount zfs with forcedirectio flag ? selim ufs directio and O_DSYNC are different things. Would a forcesync flag be something of interest to the community ? -r ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
RE: Re[2]: [zfs-discuss] writes lost with zfs !
Would a forcesync flag be something of interest to the community ? Yes. ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: Re[2]: [zfs-discuss] writes lost with zfs !
it's an absolute necessity On 3/8/07, Roch Bourbonnais [EMAIL PROTECTED] wrote: Le 8 mars 07 à 20:08, Selim Daoud a écrit : robert, this applies only if you have full control on the application forsure ..but how do you do it if you don't own the application ... can you mount zfs with forcedirectio flag ? selim ufs directio and O_DSYNC are different things. Would a forcesync flag be something of interest to the community ? -r ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] update on zfs boot support
Lin Ling wrote: Ian Collins wrote: Thanks for the heads up. I'm building a new file server at the moment and I'd like to make sure I can migrate to ZFS boot when it arrives. My current plan is to create a pool on 4 500GB drives and throw in a small boot drive. Will I be able to drop the boot drive and move / over to the pool when ZFS boot ships? Yes, should be able to, given that you have already had an UFS boot drive running root. Thanks. As I intend setting up my pool as a striped mirror, it looks from the the other postings like this will not be suitable for the boot device. So an SVM mirror on a couple of small drives may still be the best bet for a small sever. Ian ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
