On Wed, 16 Sep 2020 at 12:12, Michael Schumacher < michael.schumacher at pamas.de> wrote: > hi, > > I am planning to replace my old CentOS 6 mail server soon. Most details > are quite obvious and do not need to be changed, but the old system > was running on spinning discs and this is certainly not the best > option for todays mail servers. > > With spinning discs, HW-RAID6 was the way to go to increase reliability > and speed. > Today, I get the feeling, that traditional RAID is not the best > option for SSDs. I am reading that all RAID members in SSD-arrays age > synchronously so that the risk of a massive failure of more than one > disk is more likely than with HDDs. There are many other concerns like > excessive write load compared to non-raid systems, etc. > > Is there any common sense what disk layout should be used these days? > > I have been looking for some kind of master-slave system, where the > (one or many) SSD is taking all writes and reads, but the slave HDD > runs in parallel as a backup system like in a RAID1 system. Is there > any such system? > > I don't think so because the drives would always be out of sync but in a restart it would be hard to know if the drive is out of sync for a good reason or a bad one. For most of the SSD raids, I have seen people just making sure to buy disks which are spec'd for more writes or similar 'smarter' enterprise trim. I have also read about the synchronicity problem but I think this may be a theory vs reality problem. In theory they should all fail at once, in reality at least for the arrays I have used for 3 years, they seem to fail in different times. that said, I only have 3 systems over 3 years with SSD drives running RAID6 so I only have anecdata versus data. > Any thoughts? > > best regards > Michael Schumacher > > _______________________________________________ > CentOS mailing list > CentOS at centos.org > https://lists.centos.org/mailman/listinfo/centos > -- Stephen J Smoogen.