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<div style="font-size:10.0pt;font-family:Verdana,Arial">Actually,
mysqldump performs a lock on the records it's dumping. If its
for a MyISAM db, the entire table is locked. If it's for InnoDB
and similar, an internal snapshot is created and only the
records the dump is reading are unavailable for writing.<br>
<br>
Cyrus could also implement a per-user lock, but in reality it
doesn't need that complex syncro mechanisms, a simple global
write lock would be enough (reading would not be affected, son
only I, not I/O, and not to stop it but just to suspend). After
all, the *write* lock would last only a second or so, the fs
snapshots are almost instantaneous. If you can't tolerate a 1
second delay for writing in Cyrus, you are probably not a SME.<br>
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And you don't need to hold the data to transfer it. You can dump
it directly to a nfs share or pass it as stdout to ssh: <font
face="Courier New">mysqldump | xz -9 | ssh remote_server "cat
> /bkp/</font><font face="Courier New"><font face="Courier
New">`date +%y%m%d_%H%M`.sql.xz</font>"</font>. With a
couple of pipes more you can encrypt the data on the fly so it's
secure to store it in a cheap VPS overseas... or you could
upload it to dropbox.<br>
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1.0pt;padding:3.0pt 0cm 0cm
0cm;font-size:10.0pt;font-family:"Tahoma","sans-serif""><b>From:</b>
Jason L Tibbitts Iii<br>
<b>Sent:</b> Thursday, May 10, 2018 18:41<br>
<b>To:</b> Anatoli<br>
<b>Cc:</b> Info-cyrus<br>
<b>Subject:</b> Re: Backup methods<br>
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<pre wrap="">"A" == Anatoli <a class="moz-txt-link-rfc2396E" href="mailto:me@anatoli.ws"><me@anatoli.ws></a> writes:
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A> What about mysqldump > dump.sql, then mysql < dump.sql? Also a wrong
A> way and didn't have to be implemented?
No, that's exactly my point. Thanks for making it for me! The analog
to the way you indicated that you would like it to work would be having
the mysql server stop IO so that you can take a filesystem snapshot
while the database is in a consistent state. But instead, the database
(like cyrus) implements a backup method which you can use to extract the
data. And it also requires disk space to hold the backup until you can
transfer it to your backup medium.
- J<
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