Andrew Gabriel andrew.gabr...@oracle.com wrote:
If you go back to the late 1970's before tracks had embedded servo data,
on multi-platter disks you had one surface which contained the head
positioning servo data, and the drive relied on accurate vertical
alignment between heads/surfaces to
On Sat, Feb 5, 2011 at 3:34 PM, Roy Sigurd Karlsbakk r...@karlsbakk.net wrote:
so as not to exceed the channel bandwidth. When they need to get higher disk
capacity, they add more platters.
May this mean those drives are more robust in terms of reliability, since the
leaks between sectors is
One characteristic people often overlook is: When you get a disk with
higher capacity (say, 2T versus 600G) then you get more empty space
and hence typically lower fragmentation in the drive. Also, the
platter density is typically higher, so if the two drives have equal
RPM's, typically the
Nope. Most HDDs today have a single read channel, and they select
which head uses that channel at any point in time. They cannot use
multiple heads at the same time, because the heads to not travel the
same path on their respective surfaces at the same time. There's no
real vertical alignment
Roy Sigurd Karlsbakk wrote:
Nope. Most HDDs today have a single read channel, and they select
which head uses that channel at any point in time. They cannot use
multiple heads at the same time, because the heads to not travel the
same path on their respective surfaces at the same time. There's
For the data sheet I referenced, all the drive sizes have the same sustained
data rate OD, 125 MB/s. Eric posted an explanation for this, which
seems entirely believable: The data rate is not being limited by the density
of magnetic material on the platter or the rotational speed, but by the
From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss-
boun...@opensolaris.org] On Behalf Of taemun
Uhm. Higher RPM = higher linear speed of the head above the platter =
higher throughput. If the bit pitch (ie the size of each bit on the
platter) is the
Nope. That's what I
Edward,
Thanks for the reply.
Good point on platter density. I'ld considered the benefit of lower
fragmentation but not the possible increase in sequential iops due to density.
I assume while a 2TB 7200rpm drive may have better sequential IOPS than a
500GB, it will not be double and
From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss-
boun...@opensolaris.org] On Behalf Of James
I assume while a 2TB 7200rpm drive may have better sequential IOPS than a
500GB, it will not be double and therefore,
Don't know why you'd assume that. I would assume a 2TB drive
On Feb 2, 2011, at 6:10 AM, Edward Ned Harvey wrote:
From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss-
boun...@opensolaris.org] On Behalf Of James
I assume while a 2TB 7200rpm drive may have better sequential IOPS than a
500GB, it will not be double and therefore,
Don't
From: Richard Elling [mailto:richard.ell...@gmail.com]
They aren't. Check the datasheets, the max media bandwidth is almost
always
published.
I looked for said data sheets before posting. Care to drop any pointers? I
didn't see any drives publishing figures for throughput to/from platter
On Wed, Feb 2, 2011 at 6:10 AM, Edward Ned Harvey
opensolarisisdeadlongliveopensola...@nedharvey.com wrote:
Don't know why you'd assume that. I would assume a 2TB drive would be
precisely double the sequential throughput of a 500G. I think if you double
That's assuming that the drives have
Thanks Richard Edward for the additional contributions.
I had assumed that maximum sequential transfer rates on datasheets (btw -
those are the same for differing capacity seagate's) were based on large block
sizes and a ZFS 4kB recordsize* would mean much lower IOPS. e.g. Seagate
From: Brandon High [mailto:bh...@freaks.com]
That's assuming that the drives have the same number of platters. 500G
drives are generally one platter, and 2T drives are generally 4
platters. Same size platters, same density. The 500G drive could be
Wouldn't multiple platters of the same
From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss-
boun...@opensolaris.org] On Behalf Of James
block sizes and a ZFS 4kB recordsize* would mean much lower IOPS. e.g.
Seagate Constellations are around 75-141MB/s(inner-outer) and 75MB/s is
18750 4kB IOPS! However I've just
On Wed, Feb 2 at 20:40, Edward Ned Harvey wrote:
Wouldn't multiple platters of the same density still produce a throughput
that's a multiple of what it would have been with a single platter? I'm
assuming the heads on the multiple platters are all able to operate
simultaneously.
Nope. Most
On Wed, Feb 2 at 20:45, Edward Ned Harvey wrote:
For sustained throughput, I don't measure in IOPS. I measure in MB/s, or
Mbit/s. For a slow hard drive, 500Mbit/s. For a fast one, 1 Gbit/s or
higher. I was surprised by the specs of the seagate disks I just emailed a
moment ago. 1Gbit out
On Feb 2, 2011, at 8:10 PM, Eric D. Mudama wrote:
All other
things being equal, the 15k and the 7200 drive, which share
electronics, will have the same max transfer rate at the OD.
Is that true? So the only difference is in the access time?
Mark
Uhm. Higher RPM = higher linear speed of the head above the platter = higher
throughput. If the bit pitch (ie the size of each bit on the platter) is the
same, then surely a higher linear speed corresponds with a larger number of
bits per second?
So if all other things being equal includes the
On Thu, Feb 3 at 14:18, taemun wrote:
Uhm. Higher RPM = higher linear speed of the head above the platter =
higher throughput. If the bit pitch (ie the size of each bit on the
platter) is the same, then surely a higher linear speed corresponds with a
larger number of bits per second?
From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss-
boun...@opensolaris.org] On Behalf Of James
I’m trying to select the appropriate disk spindle speed for a proposal and
would welcome any experience and opinions (e.g. has anyone actively
chosen 10k/15k drives for a new ZFS
G'day All.
I’m trying to select the appropriate disk spindle speed for a proposal and
would welcome any experience and opinions (e.g. has anyone actively chosen
10k/15k drives for a new ZFS build and, if so, why?).
This is for ZFS over NFS for VMWare storage ie. primarily random 4kB
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