This setting general best , as most server do not benefit from it enabled. Basically only usefully in specialized server setups
Write Policy: Write Through
Generally depends on the raid type, but with SSDs the drive are so fast you would need to benchmark to see if you benefitted from WB, unlikely faster.
Disk Cache Policy: Disabled
Definitely disable, as the drives cache is not protected by battery. Even if you have a UPS, if a drive were to fail, you could lose data from the drive cache or worse. Then again some software raids have pathetic performance, relying on disk cache to result in any speed.
That is not quite true on the Disk Cache Policy. Dell SSDs have a protected cache via capacitor which saves the data even if the power goes out.
With SAS drives I found the write back cache made a huge real word difference.
Browsing a data base took 3min 20 seconds with the cache off. And only 1 min 20 seconds with the write back on.
I agree that most mechanical drives would loose the cache data but the SSDs are protected so you could leave it on. But not sure if having both caches on (SSD + Write back h700) are faster.
pcmeiners
4 Operator
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1.8K Posts
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May 26th, 2017 10:00
Read Policy: No Read Ahead.
This setting general best , as most server do not benefit from it enabled. Basically only usefully in specialized server setups
Write Policy: Write Through
Generally depends on the raid type, but with SSDs the drive are so fast you would need to benchmark to see if you benefitted from WB, unlikely faster.
Disk Cache Policy: Disabled
Definitely disable, as the drives cache is not protected by battery. Even if you have a UPS, if a drive were to fail, you could lose data from the drive cache or worse. Then again some software raids have pathetic performance, relying on disk cache to result in any speed.
I am a troll, not a robot
RAJ54
1 Rookie
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71 Posts
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October 10th, 2019 21:00
That is not quite true on the Disk Cache Policy. Dell SSDs have a protected cache via capacitor which saves the data even if the power goes out.
With SAS drives I found the write back cache made a huge real word difference.
Browsing a data base took 3min 20 seconds with the cache off. And only 1 min 20 seconds with the write back on.
I agree that most mechanical drives would loose the cache data but the SSDs are protected so you could leave it on. But not sure if having both caches on (SSD + Write back h700) are faster.
user_f6e91d
1 Message
0
December 17th, 2019 16:00
I need to use FreeNAS therefore no cache , no raid. Direct SMART control from software,. Is it posible ?