Re: Disabling Write-Caching
On Tue, Apr 10, 2007 at 01:43:54AM -0400, Greg Folkert wrote: On Tue, 2007-04-10 at 15:39 +1000, CaT wrote: On Tue, Apr 10, 2007 at 01:28:38AM -0400, Greg Folkert wrote: DB monkies generally like turning it off as it has proven to cause data loss in certain corner cases. Good DB monkies tend to be very paranoid of their data. Do these DB monkies also force multi-million dollar system with 32GB caching controllers (with battery backup for the RAM) to turn off the cache? Those tend to have HDs which properly report the status of the data (ie when theys ay 'data is on the platter' the data actually /is/ in the platter. No foolin'. I've seen it, forcing the $COMPANY to invest in even larger machines, with diminishing results. Turn cache back on, it is like a whole nuther 20 processors added. We are talking Multi-vpath stuff here. That depends on wether the gains made by turning the cache on outweigh the potential disadvantages of turning the cache on. A good DB monkey will provide said company with a risk analysis and get them to sign off on one or the other. Good DBMonkies also force the DB software to do a sync'd write through to the drives or logical drive in any case. Blah, no tthe place to discuss this vitriol. sync writes don't mean much when the HD lies. Screwy. And if they are using PATA drives on critical data, stupid. Unless they are behind a SAN or something similar... which is going to have huge caching involved caching. It all depends on the needs of the people involved and the size of their budget. -- To the extent that we overreact, we proffer the terrorists the greatest tribute. - High Court Judge Michael Kirby -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Re: Disabling Write-Caching
Jonathan Kaye: Not being one to argue, I dutifully did #hdparm -W 0 /dev/hda and now write-caching is no longer enabled. For my own reassurance, was this the sensible thing to do? You lose some write performance, but apart from that it doesn't hurt and a lot of people think it is a good idea. But please note that this setting probably doesn't survive reboots so if you want to make it permanent you have to set it in /etc/hdparm.conf. J. -- I start many things but I have yet to finish a single one. [Agree] [Disagree] http://www.slowlydownward.com/NODATA/data_enter2.html signature.asc Description: Digital signature
Re: Disabling Write-Caching
Jonathan Kaye wrote: I see that Lenny came to town yesterday. I've been tracking Testing and yesterday doing an update+upgrade gave me about 230 packages to upgrade. All went normally and my system is still purring along happily :-) I did get a warning about hdparm. It said that /dev/hda had Write chaching enabled and this was not a good idea because in the event of a power failure it could cause serious data loss. Not being one to argue, I dutifully did #hdparm -W 0 /dev/hda and now write-caching is no longer enabled. For my own reassurance, was this the sensible thing to do? TIA, Jonathan Thanks to Greg, CaT and Jochen for the feedback. Up to now I haven't noticed any degradation of performance on my desktop. If this remains the case then I'll make the change permanent otherwise it seems the risk of data loss are small, at least in my case. So if things slow down I'll re-enable the write-caching. Are there any particular tasks that would make the presence or absence of write-caching? Cheers for your advice, Jonathan -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Disabling Write-Caching
I see that Lenny came to town yesterday. I've been tracking Testing and yesterday doing an update+upgrade gave me about 230 packages to upgrade. All went normally and my system is still purring along happily :-) I did get a warning about hdparm. It said that /dev/hda had Write chaching enabled and this was not a good idea because in the event of a power failure it could cause serious data loss. Not being one to argue, I dutifully did #hdparm -W 0 /dev/hda and now write-caching is no longer enabled. For my own reassurance, was this the sensible thing to do? TIA, Jonathan -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Re: Disabling Write-Caching
On Tue, 2007-04-10 at 07:03 +0200, Jonathan Kaye wrote: I see that Lenny came to town yesterday. I've been tracking Testing and yesterday doing an update+upgrade gave me about 230 packages to upgrade. All went normally and my system is still purring along happily :-) I did get a warning about hdparm. It said that /dev/hda had Write chaching enabled and this was not a good idea because in the event of a power failure it could cause serious data loss. Not being one to argue, I dutifully did #hdparm -W 0 /dev/hda and now write-caching is no longer enabled. For my own reassurance, was this the sensible thing to do? Yeah... personally, that is someone smoking the paranoia crack. I've only ever had problems when I was using a couple of western digital drives and then it was corrected by firmware updates to the drives. (replacement from Western Digital) Show me where this has really been a problem in the last 4 years. Before then, maybe. Things have changed firmware has gotten better, write caching is still okay to use. Why else would manufacturers put cache ON-BOARD the hard-drives if it was BAD... do you think they LIKE SPENDING MONEY on things that won't be used? They would rather just not include it and save more money. -- greg, [EMAIL PROTECTED] Novell's Directory Services is a competitive product to Microsoft's Active Directory in much the same way that the Saturn V is a competitive product to those dinky little model rockets that kids light off down at the playfield. -- Thane Walkup -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Re: Disabling Write-Caching
On Tue, Apr 10, 2007 at 01:28:38AM -0400, Greg Folkert wrote: caching is still okay to use. Why else would manufacturers put cache ON-BOARD the hard-drives if it was BAD... do you think they LIKE SPENDING MONEY on things that won't be used? They would rather just not include it and save more money. To improve benchmark performance and have ever increasing numbers describing the porduct available so as to increase sales. Coincidentally it does also have a positive effect on percieved HD performance. DB monkies generally like turning it off as it has proven to cause data loss in certain corner cases. Good DB monkies tend to be very paranoid of their data. -- To the extent that we overreact, we proffer the terrorists the greatest tribute. - High Court Judge Michael Kirby -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Re: Disabling Write-Caching
On Tue, 2007-04-10 at 15:39 +1000, CaT wrote: On Tue, Apr 10, 2007 at 01:28:38AM -0400, Greg Folkert wrote: caching is still okay to use. Why else would manufacturers put cache ON-BOARD the hard-drives if it was BAD... do you think they LIKE SPENDING MONEY on things that won't be used? They would rather just not include it and save more money. To improve benchmark performance and have ever increasing numbers describing the porduct available so as to increase sales. Coincidentally it does also have a positive effect on percieved HD performance. DB monkies generally like turning it off as it has proven to cause data loss in certain corner cases. Good DB monkies tend to be very paranoid of their data. Do these DB monkies also force multi-million dollar system with 32GB caching controllers (with battery backup for the RAM) to turn off the cache? I've seen it, forcing the $COMPANY to invest in even larger machines, with diminishing results. Turn cache back on, it is like a whole nuther 20 processors added. We are talking Multi-vpath stuff here. Good DBMonkies also force the DB software to do a sync'd write through to the drives or logical drive in any case. Blah, no tthe place to discuss this vitriol. Screwy. And if they are using PATA drives on critical data, stupid. Unless they are behind a SAN or something similar... which is going to have huge caching involved caching. -- greg, [EMAIL PROTECTED] Novell's Directory Services is a competitive product to Microsoft's Active Directory in much the same way that the Saturn V is a competitive product to those dinky little model rockets that kids light off down at the playfield. -- Thane Walkup -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
