Many replies in one message.... On Mon, 02 Jul 2001 09:44:43 -0500, "Kyler B. Laird" <laird@ecn.purdue.edu> wrote:
Now I also have it run a command. It's essentially this. tail -f -n +0 Data.fs | ssh proxyhost "cat >somepath/Data.fs"
Thats a low-cost trick I hadnt thought of before, however there is still a small time in between: a) data being synced onto the main server, and the transaction succeeding b) data being written to the backup server. Data can be lost if your main machine explodes at that point. Another disadvantage to this solution; current versions of FileStore are not purely loggging; *undo* will write a single byte in the middle of the database file, which will corrupt your replica. A recent change to FileStorage handles undo a different way, which I guess that might fix this problem... Ill ask over on the zodb-dev list. On Mon, 2 Jul 2001 15:11:14 -0700 (PDT), Michel Pelletier <michel@digicool.com> wrote:
have you looked at Coda or Intermezzo? Both distributed file systems, although I've used niether.
Ive looked at them as candidates for this task, but never used them. Both of them replicate in the same 'direction' as ZEO, on reads rather than on writes, so I dont think they are suitable for this task. On 02 Jul 2001 12:13:03 -0600, Bill Anderson <bill@libc.org> wrote:
If you are running the ZSS on Linux, you can use a network block device setup that establishes a raid1 over the netwrok, and have it do a split read/write such that it only reads from the primary, but writes over the raid.
Have you tried this with FileStorage? Testing this configuration is approaching the top of my to-do list. I am a little worried that it may not be entirely stable in high-write usage, such as during a pack. (although at the moment that is just unsubstantiated FUD) If the network block device doesnt work out, I am considering patching FileStorage to distribute writes across the network, and only allow the transaction commit to complete once data is consistent across multiple remote mirrors. Of course replicated-ZEO would solve this and many other problems, but I am hoping that by concentrating on just this one use case I can develop something useful, sooner. http://www.zope.org/Wikis/DevSite/Projects/ZEOReplicatedStorage/SurviveTotal... I take it there would be willing beta testers for such a system? Toby Dickenson tdickenson@geminidataloggers.com