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Search found 8 results on 1 pages for 'symcbean'.

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• NVRAM for journals on Linux?

  - by symcbean

  I've been thinking about ways of speeding up disk I/O, and one of the bottlenecks I keep coming back to is the journal. There's an obvious benefit to using an SSD for the journal - over and above just write caching unless of course I just disable the journal with the write cache (after all devicemapper doesn't seem to support barriers). In order to get the benefits from using a BB write cache on the controller, then I'd need to disable journalling - but then the OS should try to fsck the system after an outage. Of course if the OS knows what's in the batter-backed memory then it could use it as the journal - but that means it must be exposed as a block device and only be under the control of the operating system. However I've not been able to find a suitable low-cost device (no, write-levelling for Flash is not adequate for a journal, at least one which uses Smartmedia). While there's no end of flash devices, disk/array controllers with BB write caches, so far I've not found anything which just gives me non-volatile memory addressable as a block storage device.

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• MySQL com_select?

  - by symcbean

  I'm looking to tune my query cache a bit. According to 7.6.3.4. Query Cache Status and Maintenance in the manual: The Com_select value is given by this formula: Qcache_inserts + Qcache_not_cached + queries with errors found during the column-privileges check However in 5.1.5. Server Status Variables it suggests that this is maintained by the DBMS. Having said that mysql> show status like 'Com_select%'; Always returns a value of 1 - and I'm pretty sure I've run more than one non-cached select query on my database since it started. It looks as if other people are similarly confused. Is this status variable redundant? Which bit of the manual is wrong? TIA

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• How to manage large number of desktop VMs?

  - by symcbean

  I'm looking at the feasibility of providing remote access to multiple virtual machines. The VMs themselves will provide user desktops. To make best use of the available resources, I'd like the VMs to hibernate when the user disconnects. Which implies being able to start them up when a user connects. Ideally each user would 'own' a VM image - but if not then I'd require that the session was terminated. Obviously this would require the remote access protocol to be tied into the VM management. Is there anything out there to provide such functionality? (extra credit for open protocols! ;)

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• How to produce a merged RSS feed (from DokuWiki and Serendipity)

  - by symcbean

  Hi, I've got an application developed on top of DokuWiki. I'd like to provide a 'News' page providing the latest updates from the internal RSS feed, some other feeds maintained in Serendipity and potentially other locations. Although its trivial to attach feed parsers to each one individually, I'd like to aggregate this into a single list (possibly a single RSS feed). Both the DokuWiki and Serendipity servers are not connected to the internet - so I can't use an external service for this - looking for code. Anybody got any ideas? TIA C.

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• Which event handler to use to record leaving page - onunload or onbeforeunload?

  - by symcbean

  Hi all, Having not any answers to my previous questions about using javascript to measure page turn times, I'm going to start writing my own code (!). To measure the length of tie it takes, I'm proposing dropping a cookie containing a timestamp when the user browses away from a page, then in a subsequent page, comparing that time with 'now' and sending back a request to a URL which will log the interval. It seems that there are 2 possible handlers I could associate the first block of code with - the onunload() handler or the onbeforeunload()? It's more important that it fail silently on browsers with no/broken support for the handler, than it be portable across every possible browser. Any pointers? Gotchas? TIA C.

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• Database for managing large volumes of (system) metrics

  - by symcbean

  Hi, I'm looking at building a system for managing and reporting stats on web page performance. I'll be collecting a lot more stats than are available in the standard log formats (approx 20 metrics) but compared to most types of database applications, the base data structure will be very simple. My problem is that I'll be accumulating a lot of data - in the region of 100,000 records (i.e. sets of metrics) per hour. Of course, resources are very limited! So that its possible to sensibly interact with the data, I'd need to consolidate each metric into one minute bins, broken down by URL, then for anything more than 1 day old, consolidated into 10 minute bins, then at 1 week, hourly bins. At the front end, I want to provide a view (prefereably as plots) of the last hour of data, with the facility for users to drill up/down through defined hierarchies of URLs (which do not always map directly to the hierarchy expressed in the path of the URL) and to view different time frames. Rather than coding all this myself and using a relational database, I was wondering if there were tools available which would facilitate both the management of the data and the reporting. I had a look at Mondrian however I can't see from the documentation I've looked at whether it's possible to drop the more granular information while maintaining the consolidated views of the data. RRDTool looks promising in terms of managing the data consolidation, but seems to be rather limited in terms of querying the dataset as a multi-dimensional/relational database. What else whould I be looking at?

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• Is there a sqlite entension for PHP in RedHat Enterprise Linux 5?

  - by symcbean

  Hi, I'm trying to use some off-the-shelf PHP code in RHEL5 which requires the sqlite package (not the PDO one) but it appears this is not included in the base php5.1.6 rpm bundled with RHEL5. Unfortunately, due to circumstances beyond my control, I don't have access to the installation media or RHN access (don't ask). There doesn't appear to be such a package in the CENTOS 5 distro either (and I've read that its not in the php-common rpm there either). Any ideas of where I can get this (withuot compiling my own PHP from scratch?) TIA

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• Stunnel delaying boot

  - by Onitlikesonic

  My stunnel implementation works fine when the network is plugged in but it takes an awful amount of time, which delays the whole boot process, when there is no network connected to the machine. As extra information: I'm using "delay=yes" I'm using an fqdn (e.g: stunnel.mydomain.com) for the connections Using ubuntu but this also happened with centos5 previously How can this be avoided or a timeout specified? edit: doing an strace as suggested by symcbean shows the following (including the last part where it hangs): [...] --- SIGCHLD (Child exited) @ 0 (0) --- rt_sigreturn(0x11) = 0 close(3) = 0 wait4(-1, [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], 0, NULL) = 6039 clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7ff9ce0c79d0) = 6046 wait4(-1, [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], 0, NULL) = 6046 --- SIGCHLD (Child exited) @ 0 (0) --- rt_sigreturn(0x11) = 6046 write(1, "[Started: /etc/stunnel/stunnel.c"..., 37) = 37 write(1, "stunnel.\n", 9) = 9 exit_group(0) = ? [...] stunnel hangs in this line: wait4(-1, and when i plug in the network cable it continues to show [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], 0, NULL) = 6046

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