On 2015-05-20 21:08, Cejka Rudolf wrote: > Dimitri Maziuk wrote (2015/05/20):
>> 160 < 180. >> >> you get it now? > > It should be "min. 160 < max. 180", which is false. Actually, no: "up to" 160 so max. vs max. > Tape users usually do not want to switch off hardware tape drive > compression and use slower/faster better/worse software compression > instead of it. Hence comparing to write to zfs with compression on: 340MB/s observed to disk vs "up to 400MB/s" LTO sales pitch. (IRL you probably want to compress on the client before you push it over the network so compression on the storage becomes not so big a deal.) ...Also, max. disk speeds are just at the beginning of > the disk. That's the other part that ticks me off: don't compare the top of the line tape drive to a cheapest "desktop" drive. E.g. seagate's 15K "performance" line claims 240MB/s on the outside sectors and 140-ish (IIRC) on the inside: uncompressed head to platter. Yes, they do spell it out in that price bracket. > And when the disk is not new, there could be very annoying speed > instabilities due to internal sector reallocations and some other > mysteries with no-so-bad/good sectors and heads. It's called TLER and it's why you pay extra $20 for "nas" drive instead of the "desktop" one. But again, if you're comparing drive to tape: talk about when tape and drive aren't new: loose pins and worn motors that pull and stretch mylar and all that. Otherwise it's apples to oranges. ... I have seen small LBA > interval slow downs even up to just 1 MB/s on one 2 TB drive, and the > drive still reported very good SMART values - no reallocations, no > errors. Yes, I've thrown away a few of those. I've also thrown away a couple of LSI hardware raid cards (re your other post) recently and replaced them with basic "hba" controllers and zfs: flakey firmware, awful software, raids are not expandable, etc., etc. At this point my take on hardware raid is: "avoid like plague", if you need the speed add $5 and buy SSDs. Dimitri ------------------------------------------------------------------------------ One dashboard for servers and applications across Physical-Virtual-Cloud Widest out-of-the-box monitoring support with 50+ applications Performance metrics, stats and reports that give you Actionable Insights Deep dive visibility with transaction tracing using APM Insight. http://ad.doubleclick.net/ddm/clk/290420510;117567292;y _______________________________________________ Bacula-users mailing list Bacula-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bacula-users
