On 10. juni. 2009, at 20.41, Roy Sigurd Karlsbakk wrote:
Hi all
I've been reading up a little about data deduplication, and have
been in search for an OSS filesystem with dedup without much luck.
While testing snapshots and so on in LVM, I started wondering if
dedup would be better off in LVM than in the filesystem. Would it be
possible/efficient to add dedup to the LVM layer, or perhaps a layer
above LVM? This could make dedup work for all or most of
filesystems. Make a hash table with 4k (or whatever) blocks, make
virtual blocks pointing to the physical blocks and run a remapping/
deduping job at night. If written to, copy-on-write could be used to
increase speed.
Answering myself, it seems there can be a problem with this without a
rather large change in the APIs. If I understand it correctly, if
metadata is deduplicated, it may impose a rather large performance
impact on writes, and from the block layer, how do you know what's
metadata and what's not?
roy
--
Roy Sigurd Karlsbakk
(+47) 97542685
roy@karlsbakk.net
http://blogg.karlsbakk.net/
--
I all pedagogikk er det essensielt at pensum presenteres
intelligibelt. Det er et elementært imperativ for alle pedagoger å
unngå eksessiv anvendelse av idiomer med fremmed opprinnelse. I de
fleste tilfeller eksisterer adekvate og relevante synonymer på norsk.
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