Path: csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!news.albasani.net!eternal-september.org!feeder.eternal-september.org!.POSTED!not-for-mail From: Tim Watts Newsgroups: comp.databases.mysql Subject: Re: Can MySql database store images? Followup-To: comp.databases.mysql Date: Mon, 25 Apr 2011 13:36:59 +0100 Organization: A noiseless patient Spider Lines: 44 Message-ID: References: <4db54728$0$81481$e4fe514c@news.xs4all.nl> <840g88-ece.ln1@squidward.dionic.net> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7Bit Injection-Info: mx03.eternal-september.org; posting-host="6oIlEBqCjOm0MjsSUEk5CA"; logging-data="14661"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX18S7z0XPH3lyILVWPku9jKXp4egq5UmK3M=" User-Agent: KNode/4.4.6 Cancel-Lock: sha1:tVZs2QMaH8QSkJBRzFsQvphDr34= Xref: x330-a1.tempe.blueboxinc.net comp.databases.mysql:670 Jerry Stuckle wrote: > On 4/25/2011 6:48 AM, Tim Watts wrote: >> Jerry Stuckle wrote: >> >>> On 4/25/2011 6:04 AM, Luuk wrote: >>>> On 24-04-2011 23:34, Jerry Stuckle wrote: >>>>> Additionally, RDBMS's can partition data for faster access, i.e. >>>>> across >>>>> multiple disks or even multiple systems. Filesystems cannot do that >>>>> transparently. >>>> >>>> File systems can do that, they invented something like directory's for >>>> that. >>>> >>>> A different toy needs different tools... >>>> >>> >>> Name a file system which transparently partitions a directory across >>> multiple systems. >>> >> >> ZFS >> >> Any file system on top of LVM or EVMS. >> > > And if I'm not mistaken, it's subdirectories which are spread across > multiple disks - not files in one directory. > I'm not sure in the case of ZFS, but with LVM or EVMS (though that's pretty dead now) the spreading is done at the block level so what bits of what files end up where is pretty random. LVM is not filesystem aware and the FS on top has only the awareness of LVM that may have been hinted to it at mkfs time (ie for optimising stripe size etc) and that cannot be trusted as absolute. ZFS is of course aware of the FS and the block devices as it spans all the layers, but as to whether it deliberately tries to keep one directory localised I do not know - but it would seem to be an unecessary and pointless limitation for it to try to do so. -- Tim Watts