I'm trying to get into the world of home file servers (or an NAS, I'm not really sure what the difference is) and there's a lot of information on how to start. There are a few things that I would like to see, get a feel for, and hear other peoples' opinions on.
What are some of the best... (5 Replies)
Hi all,
We have a disk array that has the boot drive on an OCZ SSD on a PCIe card. Well, the motherboard died and we got a new motherboard. We moved the controllers, NICs, etc, to the exact same slots on the new motherboard, except now it won't boot. I guess it doesn't recognize the OS on the... (1 Reply)
I have an upgrade path in mind for a new computer that will be stocked with a 2TB SATA 300 hard disk. This is a choice based on information that SATA 300 is not necessarily faster than SATA 600. The upgrade path in a year time or so would then involve the purchase of an SSD that would contain the... (4 Replies)
Hello everybody,
I need to connect a laptop 2.5 SATA hard drive to a Desktop board (which uses 3.5' SATA hard drives). I've tried the connectors and they fit excellent in the 2.5 SATA connectors.
The problem is that the laptop hard drive uses 5v and the PC's power source sends 12v. So, my... (4 Replies)
trying to setup a sata drive using a sata to scsi adaptor
I have a sata 1TB Deskstar that I had setup before and during shipment from a facilty to another, the disk failed. The handling was not great, lots of throwing boxes, etc. I have a new disk from Hitachi (thankyou Hitachi) anyway, I don't... (1 Reply)
i have a network drive (samba) mounted on to my PC and also i have SSH client on my machine. however i need to run applications/commands on a unix server from the middle of a different executable(windows compatable one). so i need to connect to the unix server from SSH through the... (1 Reply)
DMC(1)DMC(1)NAME
dmc - controls the Disk Mount Conditioner
SYNOPSIS
dmc start mount [profile-name|profile-index [-boot]]
dmc stop mount
dmc status mount [-json]
dmc show profile-name|profile-index
dmc list
dmc select mount profile-name|profile-index
dmc configure mount type access-time read-throughput write-throughput [ioqueue-depth maxreadcnt maxwritecnt segreadcnt segwritecnt]
dmc help | -h
DESCRIPTION dmc(1) configures the Disk Mount Conditioner. The Disk Mount Conditioner is a kernel provided service that can degrade the disk I/O being
issued to specific mount points, providing the illusion that the I/O is executing on a slower device. It can also cause the conditioned
mount point to advertise itself as a different device type, e.g. the disk type of an SSD could be set to an HDD. This behavior consequently
changes various parameters such as read-ahead settings, disk I/O throttling, etc., which normally have different behavior depending on the
underlying device type.
COMMANDS
Common command parameters:
o mount - the mount point to be used in the command
o profile-name - the name of a profile as shown in dmc list
o profile-index - the index of a profile as shown in dmc list
dmc start mount [profile-name|profile-index [-boot]]
Start the Disk Mount Conditioner on the given mount point with the current settings (from dmc status) or the given profile, if pro-
vided. Optionally configure the profile to remain enabled across reboots, if -boot is supplied.
dmc stop mount
Disable the Disk Mount Conditioner on the given mount point. Also disables any settings that persist across reboot via the -boot flag
provided to dmc start, if any.
dmc status mount [-json]
Display the current settings (including on/off state), optionally as JSON
dmc show profile-name|profile-index
Display the settings of the given profile
dmc list
Display all profile names and indices
dmc select mount profile-name|profile-index
Choose a different profile for the given mount point without enabling or disabling the Disk Mount Conditioner
dmc configure mount type access-time read-throughput write-throughput [ioqueue-depth maxreadcnt maxwritecnt segreadcnt segwritecnt]
Select custom parameters for the given mount point rather than using the settings provided by a default profile.
See dmc list for example parameter settings for various disk presets.
o type - 'SSD' or 'HDD'. The type determines how various system behaviors like disk I/O throttling and read-ahead algorithms affect the
issued I/O. Additionally, choosing 'HDD' will attempt to simulate seek times, including drive spin-up from idle.
o access-time - latency in microseconds for a single I/O. For SSD types this latency is applied exactly as specified to all I/O. For HDD
types, the latency scales based on a simulated seek time (thus making the access-time the maximum latency or seek penalty).
o read-throughput - integer specifying megabytes-per-second maximum throughput for disk reads
o write-throughput - integer specifying megabytes-per-second maxmimu throughput for disk writes
o ioqueue-depth - maximum number of commands that a device can accept
o maxreadcnt - maximum byte count per read
o maxwritecnt - maximum byte count per write
o segreadcnt - maximum physically disjoint segments processed per read
o segwritecnt - maximum physically disjoint segments processed per write
dmc help | -h
Display help text
EXAMPLES
dmc start / '5400 HDD'
Turn on the Disk Mount Conditioner for the boot volume, acting like a 5400 RPM hard drive.
dmc configure /Volumes/ExtDisk SSD 100 100 50
Configure an external disk to use custom parameters to degrade performance as if it were a slow SSD with 100 microsecond latencies,
100MB/s read throughput, and 50MB/s write throughput.
IMPORTANT
The Disk Mount Conditioner is not a 'simulator'. It can only degrade (or 'condition') the I/O such that a faster disk device behaves like a
slower device, not vice-versa. For example, a 5400 RPM hard drive cannot be conditioned to act like a SSD that is capable of a higher
throughput than the theoretical limitations of the hard disk.
In addition to running dmc stop, rebooting is also a sufficient way to clear any existing settings and disable Disk Mount Conditioner on
all mount points (unless started with -boot).
SEE ALSO nlc(1)
January 2018 DMC(1)