Re: [zfs-discuss] ZFS forensics/revert/restore shellscript and how-to.
Hi Fred, Have you read the ZFS On Disk Format Specification paper at: http://hub.opensolaris.org/bin/download/Community+Group+zfs/docs/ondiskformat0822.pdf? Ifred pam wrote: Hi Richard, thanks for your time, I really appreciate it, but I'm still unclear on how this works. So uberblocks point to the MOS. Why do you then require multiple uberblocks? Or are there actually multiple MOS'es? Or is there one MOS and multiple delta's to it (and its predecessors) and do the uberblocks then point to the latest delta? In the latter case I can understand why Nullifying the latest uberblocks reverts to a previous situation, otherwise I don't see the difference between "Nullifying the first uberblocks" and "Nullifying the last uberblocks". One reason for multiple uberblocks is that uberblocks, like everything else, are copy-on-write. The reason you have 4 copies (2 labels at front and 2 labels at the end of every disk) is redundancy. No, there are not multiple MOS'es in one pool (though there may be multiple copies of the MOS via "ditto" blocks). The current (or "active") uberblock is the one with the highest transaction id with valid checksum. Transaction ids are basically monotonically increasing, so nullifying the last uberblock can revert you to a previous state. max Thanks, Fred ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Tuning the ARC towards LRU
Hi, In simple terms, the ARC is divided into a MRU and MFU side. target size (c) = target MRU size (p) + target MFU size (c-p) On Solaris, to get from the MRU to the MFU side, the block must be read at least once in 62.5 milliseconds. For pure read-once workloads, the data won't to the MFU side and the ARC will behave exactly like an (adaptable) MRU cache. Richard, I am looking at the code that moves a buffer from MRU to MFU, and as I read it, if the block is read and the time is greater than 62 milliseconds, it moves from MRU to MFU (lines ~2256 to ~2265 in arc.c). Also, I have a program that reads the same block once every 5 seconds, and on a relatively idle machine, I can find the block in the MFU, not the MRU (using mdb). If the block is read again in less than 62 milliseconds, it stays in the MRU. max ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] ZFS hex dump diagrams?
Hi Richard, Richard Elling wrote: On Mar 25, 2010, at 2:45 PM, John Bonomi wrote: I'm sorry if this is not the appropriate place to ask, but I'm a student and for an assignment I need to be able to show at the hex level how files and their attributes are stored and referenced in ZFS. Are there any resources available that will show me how this is done? IMHO the best place to start with this level of analysis is the ZFS on-disk specification doc: http://hub.opensolaris.org/bin/download/Community+Group+zfs/docs/ondiskformat0822.pdf It is getting long in the tooth and doesn't document recent features, but it is fundamentally correct. I completely agree with this, but good luck getting a hex dump from that information. max ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] ZFS hex dump diagrams?
Hi, You might take a look at http://www.osdevcon.org/2008/files/osdevcon2008-max.pdf and http://www.osdevcon.org/2008/files/osdevcon2008-proceedings.pdf, starting at page 36. Or you might just use "od -x file" for the file part of your assignment. Have fun. max Eric D. Mudama wrote: On Fri, Mar 26 at 11:10, Sanjeev wrote: On Thu, Mar 25, 2010 at 02:45:12PM -0700, John Bonomi wrote: I'm sorry if this is not the appropriate place to ask, but I'm a student and for an assignment I need to be able to show at the hex level how files and their attributes are stored and referenced in ZFS. Are there any resources available that will show me how this is done? You could try zdb. Or just look at the source code. ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] ZIL corrupt, not recoverable even with logfix
Hi James, I just spent about a week recovering about 10TB of file data for someone who encountered a (somewhat?) similar problem to what you are seeing. If you are still having problems with this, please contact me off-list. Regards, max James Risner wrote: It was created on AMD64 FreeBSD with 8.0RC2 (which was version 13 of ZFS iirc.) At some point I knocked it out (export) somehow, I don't remember doing so intentionally. So I can't do commands like zpool replace since there are no pools. It says it was last used by the FreeBSD box, but the FreeBSD does not show it with "zpool status" command. I'm going down tomorrow to work on it again, and I'm going to try 8.0 Release AMD64 FreeBSD (I've already tried i386 AMD64 FreeBSD 8.0 Release) and Opensolaris dev-127. I was just hoping there was some way I'm missing to mount it read only (I have tried "zpool import -f -o readonly=yes" but that doesn't work either.) ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Zfs improvements to compression in Solaris 10?
Hi Bob, Bob Friesenhahn wrote: On Tue, 4 Aug 2009, Prabahar Jeyaram wrote: You seem to be hitting : http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6586537 The fix is available in OpenSolaris build 115 and later not for Solaris 10 yet. It is interesting that this is a simple thread priority issue. The system has a ton of available CPU but the higher priority compression thread seems to cause scheduling lockout. The Perfmeter tool shows that compression is a very short-term spike in CPU. Of course since Perfmeter and other apps stop running, it might be missing some sample data. I could put the X11 server into the real-time scheduling class but hate to think about what would happen as soon as Firefox visits a web site. :-) I can understand wanting to be careful about running Xorg real time, but what does this have to do with firefox? Firefox will still run in the interactive class. max ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Best ways to contribute WAS: Fed up with ZFS causing data loss
Hi Ross, Ross wrote: #3 zfs unlike other things like the build system are extremely well documented. There are books on it, code to read and even instructors (Max Bruning) who can teach you about the internals. My project even rganized a free online training for this Again, brilliant if you're a programmer. I think it is a misconception that a course about internals is meant only for programmers. An internals course should teach how the system works. If you are a programmer, this should help you to do programming on the system. If you are an admin, it should help you in your admin work by giving you a better understanding of what the system is doing. If you are a user, it should help you to make better use of the system. In short, I think anyone who is working with Solaris/OpenSolaris can benefit. max ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] raidz on-disk layout
Hi, For anyone interested, I have blogged about raidz on-disk layout at: http://mbruning.blogspot.com/2009/04/raidz-on-disk-format.html Comments/corrections are welcome. thanks, max ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Real Swap space & vmstat output
Hi, iman habibi wrote: Hi to All I defined 2G for swap space in installation solaris 10 with zfs file system,,but when i run vmstat it shows about 3G is free!.why this happend?! My Real memory is 4G. Can anybody guide this,,im confused! # vmstat 10 kthr memorypagedisk faults cpu r b w swap free re mf pi po fr de sr s6 sd sd sd in sy cs us sy id 0 0 0 3875248 2385176 0 1 0 0 0 0 0 -0 -0 -0 2 1764 38933 10834 29 36 36 1 0 0 3590808 2091536 1 2 0 0 0 0 0 0 0 0 0 2316 57731 14530 43 53 4 0 0 0 3590824 2091616 0 0 0 0 0 0 0 0 0 0 2 2176 57499 14528 43 52 5 0 0 0 3590816 2091608 0 0 0 0 0 0 0 0 0 0 0 2417 57756 14481 43 52 5 1 0 0 3590808 2091600 0 0 0 0 0 0 0 0 0 0 0 2525 57154 14249 44 53 3 0 0 0 3590808 2091600 0 0 0 0 0 0 0 0 0 0 2 2964 57376 14483 43 53 4 ^C # zpool list NAMESIZE USED AVAILCAP HEALTH ALTROOT rpool68G 6.67G 61.3G 9% ONLINE - # zfs list NAMEUSED AVAIL REFER MOUNTPOINT rpool 8.67G 58.3G94K /rpool rpool/ROOT 4.61G 58.3G18K legacy rpool/ROOT/s10s_u6wos_07b 4.61G 58.3G 4.38G / rpool/ROOT/s10s_u6wos_07b/var 230M 58.3G 230M /var rpool/dump 1.00G 58.3G 1.00G - rpool/export 1.06G 58.3G20K /export rpool/export/home 1.06G 58.3G 1.06G /export/home rpool/swap2G 60.3G16K - A short answer is that the swap column from vmstat is showing the amount of free space usable for anonymous memory. This includes free space on disk plus usable space in memory. You should also take a look at "swap -lh" and "swap -sh" output. max Regards ___ 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
