… time to turn off write-cache on SSD – all transactions are in place now, but write speed is only 1200 writes / s, which is… writes / s, this is because LVM ignores write barriers (see http://dammit.lt/2008/11/03/xfs-write-barriers/ ), but again with enable write-cache… solution could be put SSD into RAID controller with battery-backup-ed write cache, but I am not sure what is good ones…
Post: Looking for RAID Controller without Battery Learning problems ?
January 5, 2012 By 7 Comments
… Read-cache mode : Enabled MaxIQ preferred cache setting : Disabled MaxIQ cache setting : Disabled Write-cache mode : Enabled (write-back) Write-cache setting : Enabled (write-back) when protected by battery/ZMM… currently operating in Write-Back cache mode now (Write-Cache mode line) and it is set into “Enabled (write-back) when protected by battery/ZMM”, which…
Post: Battery Learning still problem many years after
February 10, 2011 By 7 Comments
…_write_io_threads to get more outstanding requests – without cache it matters a lot for writes. This is a lot better than forcing write cache without Battery as database should not…
Post: Testing the Group Commit Fix
July 13, 2011 By 13 Comments
… also appear when being on battery and your RAID card dies, automatically switching from write-back to write-through cache mode. We benchmarked the… set and write-back cache is not enabled. Write-back cache is must-have for an environment demanding performance, of course, yet batteries periodically die… are for binaries with group commit fix. Results with disabled write cache thread trx=1, No binlog trx=0, No binlog trx…
Post: The perils of uniform hardware and RAID auto-learn cycles
November 16, 2010 By 16 Comments
… machines. The result: the battery-backed cache was in write-through mode instead of write-back mode, and the battery was at 33% and charging. We quickly checked a few other sick machines. Same thing — write-through, battery charging. And the battery…
Post: How Percona does a MySQL Performance Audit
November 24, 2008 By 17 Comments
… how to build for massive scalability, how to do read-write splitting without breaking the user experience, how to take online… are. I can also get information about the all-important battery-backed write cache, how it’s configured and what its status is… server’s variables or whatever other data I need, and write something instructional to the client about it. Preparing to report…
Comment: Tokyo Tyrant - The Extras Part I : Is it Durable?
August 20, 2010 By 5 Comments
… your I/O buffers & cache to actually be *smaller* might help, avoiding the pitfall of big deferred writes or having to make… buffer/caches might be tuned for certain times of the day/month/year for the a write-intensive periods of heavy writes to… the loop. Also a good HDD controller would have a cache battery that ensures buffers are flushed if there’s power interruption…
Post: FlashCache: more benchmarks
May 18, 2010 By 15 Comments
… than cache. But before test setup let me address some concern (which I also had). Intel X25-M has a write cache which is not battery backuped, so there is suspect you may have data… exactly where to write data..”. So I assume we should be safe running Intel X25-M with enabled write cache. Second issue I…
Comment: Should I buy a Fast SSD or more memory?
April 20, 2010 By 10 Comments
Frank, As long as you have a battery backed write cache the nobarrier option is safe, and in fact recommended. See … persistent write cache? Many hardware RAID have a persistent write cache which preserves it across power failure, interface resets, system crashes, etc. Using write barriers…
Comment: Is your server's performance about to degrade?
May 18, 2010 By 13 Comments
Also keep an eye out for RAID cards testing their battery — they do that by disabling the battery-backed write cache in order to test-drain the battery. Can wreak havoc on a server “randomly”.
