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Hardware: reworked for sphinx

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George Melikov
2020-09-13 14:22:39 +03:00
parent c5b576c873
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docs/Performance and Tuning/Hardware.rst
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@@ -1,3 +1,6 @@
Hardware
********
Introduction Introduction
============ ============
@@ -196,8 +199,7 @@ not be as reliable as it would be on its own.
misreports its sector size. Such drives are typically NAND-flash misreports its sector size. Such drives are typically NAND-flash
based solid state drives and older SATA drives from the advanced based solid state drives and older SATA drives from the advanced
format (4K sector size) transition before Windows XP EoL occurred. format (4K sector size) transition before Windows XP EoL occurred.
This can be `manually This can be :ref:`manually corrected <alignment_shift_ashift>` at
corrected <Performance_tuning#Alignment_Shift_.28ashift.29>`__ at
vdev creation. vdev creation.
- It is possible for the RAID header to cause misalignment of sector - It is possible for the RAID header to cause misalignment of sector
writes on RAID 1 by starting the array within a sector on an writes on RAID 1 by starting the array within a sector on an
@@ -387,8 +389,8 @@ requires command queuing. Almost all drives manufactured within the past
system BIOS. system BIOS.
Each Open ZFS system has different methods for checking whether command Each Open ZFS system has different methods for checking whether command
queuing is supported. On Linux, \`hdparm -I /path/to/device \| grep queuing is supported. On Linux, ``hdparm -I /path/to/device \| grep
Queue\` is used. On FreeBSD, \`camcontrol identify $DEVICE\` is used. Queue`` is used. On FreeBSD, ``camcontrol identify $DEVICE`` is used.
.. _nand_flash_ssds: .. _nand_flash_ssds:
@@ -425,13 +427,13 @@ NVMe drives should be
to use 4096-byte sectors without metadata prior to being given to ZFS to use 4096-byte sectors without metadata prior to being given to ZFS
for best performance unless they indicate that 512-byte sectors are as for best performance unless they indicate that 512-byte sectors are as
performant as 4096-byte sectors, although this is unlikely. Lower performant as 4096-byte sectors, although this is unlikely. Lower
numbers in the Rel_Perf of Supported LBA Sizes from \`smartctl -a numbers in the Rel_Perf of Supported LBA Sizes from ``smartctl -a
/dev/$device_namespace\` (for example \`smartctl -a /dev/nvme1n1`) /dev/$device_namespace`` (for example ``smartctl -a /dev/nvme1n1``)
indicate higher performance low level formats, with 0 being the best. indicate higher performance low level formats, with 0 being the best.
The current formatting will be marked by a plus sign under the format The current formatting will be marked by a plus sign under the format
Fmt. Fmt.
You may format a drive using \`nvme format /dev/nvme1n1 -l $ID`. The $ID You may format a drive using ``nvme format /dev/nvme1n1 -l $ID``. The $ID
corresponds to the Id field value from the Supported LBA Sizes SMART corresponds to the Id field value from the Supported LBA Sizes SMART
information. information.
@@ -453,12 +455,12 @@ the drive firmware is not available for review, the traditional
conclusion was that all drives that lack hardware features to avoid conclusion was that all drives that lack hardware features to avoid
power failure events cannot be trusted, which was found to be the case power failure events cannot be trusted, which was found to be the case
multiple times in the multiple times in the
past\ `1 <http://lkcl.net/reports/ssd_analysis.html>`__\ `2 <https://www.usenix.org/system/files/conference/fast13/fast13-final80.pdf>`__\ `3 <http://blog.nordeus.com/dev-ops/power-failure-testing-with-ssds.htm>`__. past [#ssd_analysis]_ [#ssd_analysis2]_ [#ssd_analysis3]_.
Discussion of power failures bricking NAND flash SSDs appears to have Discussion of power failures bricking NAND flash SSDs appears to have
vanished from literature following the year 2015. SSD manufacturers now vanished from literature following the year 2015. SSD manufacturers now
claim that firmware power loss protection is robust enough to provide claim that firmware power loss protection is robust enough to provide
equivalent protection to hardware power loss protection. Kingston is one equivalent protection to hardware power loss protection. `Kingston is one
example\ `4 <https://www.kingston.com/us/solutions/servers-data-centers/ssd-power-loss-protection>`__. example <https://www.kingston.com/us/solutions/servers-data-centers/ssd-power-loss-protection>`__.
Firmware power loss protection is used to guarantee the protection of Firmware power loss protection is used to guarantee the protection of
flushed data and the drives’ own metadata, which is all that filesystems flushed data and the drives’ own metadata, which is all that filesystems
such as ZFS need. such as ZFS need.
@@ -577,8 +579,8 @@ follows:
- Intel 320 - Intel 320
- Early reports claimed that the 330 and 335 had power failure - Early reports claimed that the 330 and 335 had power failure
protection too, but they do protection too, `but they do
not.\ `5 <http://blog.nordeus.com/dev-ops/power-failure-testing-with-ssds.htm>`__ not <http://blog.nordeus.com/dev-ops/power-failure-testing-with-ssds.htm>`__.
- Intel 710 - Intel 710
- Intel 730 - Intel 730
@@ -594,8 +596,8 @@ follows:
- Samsung 845DC Evo - Samsung 845DC Evo
- Samsung 845DC Pro - Samsung 845DC Pro
- High sustained write - `High sustained write
IOPS\ `6 <http://www.anandtech.com/show/8319/samsung-ssd-845dc-evopro-preview-exploring-worstcase-iops/5>`__ IOPS <http://www.anandtech.com/show/8319/samsung-ssd-845dc-evopro-preview-exploring-worstcase-iops/5>`__
- Toshiba HK4E/HK3E2 - Toshiba HK4E/HK3E2
- Toshiba HK4R/HK3R2/HK3R - Toshiba HK4R/HK3R2/HK3R
@@ -621,7 +623,7 @@ protects flushed data is sufficient for ZFS to ensure that data remains
safe. safe.
Anyone who believes an unlisted drive to provide adequate power failure Anyone who believes an unlisted drive to provide adequate power failure
protection may contact the `OpenZFS mailing list <mailing_list>`__ with protection may contact the :ref:`mailing_lists` with
a request for inclusion and substantiation for the claim that power a request for inclusion and substantiation for the claim that power
failure protection is provided. Examples of substantiation include failure protection is provided. Examples of substantiation include
pictures of drive internals showing the presence of capacitors, pictures of drive internals showing the presence of capacitors,
@@ -640,7 +642,7 @@ Flash pages
The smallest unit on a NAND chip that can be written is a flash page. The smallest unit on a NAND chip that can be written is a flash page.
The first NAND-flash SSDs on the market had 4096-byte pages. Further The first NAND-flash SSDs on the market had 4096-byte pages. Further
complicating matters is that the the page size has been doubled twice complicating matters is that the the page size has been doubled twice
since then. NAND flash SSDs \*should\* report these pages as being since then. NAND flash SSDs **should** report these pages as being
sectors, but so far, all of them incorrectly report 512-byte sectors for sectors, but so far, all of them incorrectly report 512-byte sectors for
Windows XP compatibility. The consequence is that we have a similar Windows XP compatibility. The consequence is that we have a similar
situation to what we had with early advanced format hard drives. situation to what we had with early advanced format hard drives.
@@ -695,8 +697,8 @@ need to run TRIM on them. However, they cost more per GB than NAND flash
(as of 2020). The enterprise models make excellent SLOG devices. Here is (as of 2020). The enterprise models make excellent SLOG devices. Here is
a list of models that are known to perform well: a list of models that are known to perform well:
- Intel DC - `Intel DC
P4800X\ `7 <https://www.servethehome.com/intel-optane-hands-on-real-world-benchmark-and-test-results/>`__ P4800X <https://www.servethehome.com/intel-optane-hands-on-real-world-benchmark-and-test-results/>`__
- This gives basically the highest performance you can get as of - This gives basically the highest performance you can get as of
June 2020. June 2020.
@@ -793,5 +795,13 @@ UPS batteries
The lead acid batteries in UPS units generally need to be replaced The lead acid batteries in UPS units generally need to be replaced
regularly to ensure that they provide power during power outages. For regularly to ensure that they provide power during power outages. For
home systems, this is every 3 to 5 years, although this varies with home systems, this is every 3 to 5 years, although this varies with
temperature\ `8 <https://www.apc.com/us/en/faqs/FA158934/>`__. For temperature [#ups_temp]_. For
enterprise systems, contact your vendor. enterprise systems, contact your vendor.
.. rubric:: Footnotes
.. [#ssd_analysis] <http://lkcl.net/reports/ssd_analysis.html>
.. [#ssd_analysis2] <https://www.usenix.org/system/files/conference/fast13/fast13-final80.pdf>
.. [#ssd_analysis3] <http://blog.nordeus.com/dev-ops/power-failure-testing-with-ssds.htm>
.. [#ups_temp] <https://www.apc.com/us/en/faqs/FA158934/>