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I came across the following blurb in some RHEL 6 training documentation:

The number of drives that can be installed on modern computers has increased. With port multipliers, it's relatively easy to configure 16 Serial Advanced Technology Attachment (SATA) drives on a system (assuming you can fit all of those drives).

Does this mean that RHEL 6 won't allow more than 16 SATA drives from a software perspective? Or just that practical hardware constraints usually don't allow for more than 16 but it's technically possible?

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I have personally used 36 SATA drive chassis in RHEL/CentOS 5 and 6. – jordanm Jan 12 '13 at 22:24
up vote 1 down vote accepted

RHEL's limitations are core- and RAM-based, not drive count-based; the wording is hinting at few chassis being able to mount more than 10 or so drives. Linux itself is limited to 128 SCSI drive devices (sda through sddx).

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Thanks for the clarification. That interesting - the training documentation also mentions that "depending on the SCSI hardware available, you can attach up to 31 different SCSI hard drive". I wonder where they got that number? – Mike B Jan 12 '13 at 22:07
That refers specifically to SCSI interface hard drives. sdX devices include PATA, SATA, USB, etc. interface hard drives as well. – Ignacio Vazquez-Abrams Jan 12 '13 at 22:08
Another note is that a hardware RAID array is seen by the OS as a single SCSI device. – jordanm Jan 12 '13 at 22:22

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