1 '\" te
   2 .\" Copyright (c) 2013, 2016 by Delphix. All rights reserved.
   3 .\" Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
   4 .\" Copyright (c) 2014, Joyent, Inc. All rights reserved.
   5 .\" Copyright (c) 2014 Integros [integros.com]

   6 .\" The contents of this file are subject to the terms of the Common Development
   7 .\" and Distribution License (the "License").  You may not use this file except
   8 .\" in compliance with the License. You can obtain a copy of the license at
   9 .\" usr/src/OPENSOLARIS.LICENSE or http://www.opensolaris.org/os/licensing.
  10 .\"
  11 .\" See the License for the specific language governing permissions and
  12 .\" limitations under the License. When distributing Covered Code, include this
  13 .\" CDDL HEADER in each file and include the License file at
  14 .\" usr/src/OPENSOLARIS.LICENSE.  If applicable, add the following below this
  15 .\" CDDL HEADER, with the fields enclosed by brackets "[]" replaced with your
  16 .\" own identifying information:
  17 .\" Portions Copyright [yyyy] [name of copyright owner]
  18 .TH ZPOOL-FEATURES 5 "Aug 27, 2013"
  19 .SH NAME
  20 zpool\-features \- ZFS pool feature descriptions
  21 .SH DESCRIPTION
  22 .LP
  23 ZFS pool on\-disk format versions are specified via "features" which replace
  24 the old on\-disk format numbers (the last supported on\-disk format number is
  25 28). To enable a feature on a pool use the \fBupgrade\fR subcommand of the
  26 \fBzpool\fR(1M) command, or set the \fBfeature@\fR\fIfeature_name\fR property
  27 to \fBenabled\fR.
  28 .sp
  29 .LP
  30 The pool format does not affect file system version compatibility or the ability
  31 to send file systems between pools.
  32 .sp
  33 .LP
  34 Since most features can be enabled independently of each other the on\-disk
  35 format of the pool is specified by the set of all features marked as
  36 \fBactive\fR on the pool. If the pool was created by another software version
  37 this set may include unsupported features.
  38 .SS "Identifying features"

 469 .RE
 470 .sp
 471 .ne 2
 472 .na
 473 \fB\fBlarge_blocks\fR\fR
 474 .ad
 475 .RS 4n
 476 .TS
 477 l l .
 478 GUID    org.open-zfs:large_block
 479 READ\-ONLY COMPATIBLE   no
 480 DEPENDENCIES    extensible_dataset
 481 .TE
 482 
 483 The \fBlarge_block\fR feature allows the record size on a dataset to be
 484 set larger than 128KB.
 485 
 486 This feature becomes \fBactive\fR once a \fBrecordsize\fR property has been
 487 set larger than 128KB, and will return to being \fBenabled\fR once all
 488 filesystems that have ever had their recordsize larger than 128KB are destroyed.

 489 .RE
 490 





















































































 491 .sp
 492 .ne 2
 493 .na
 494 \fB\fBsha512\fR\fR
 495 .ad
 496 .RS 4n
 497 .TS
 498 l l .
 499 GUID    org.illumos:sha512
 500 READ\-ONLY COMPATIBLE   no
 501 DEPENDENCIES    extensible_dataset
 502 .TE
 503 
 504 This feature enables the use of the SHA-512/256 truncated hash algorithm
 505 (FIPS 180-4) for checksum and dedup. The native 64-bit arithmetic of
 506 SHA-512 provides an approximate 50% performance boost over SHA-256 on
 507 64-bit hardware and is thus a good minimum-change replacement candidate
 508 for systems where hash performance is important, but these systems
 509 cannot for whatever reason utilize the faster \fBskein\fR and
 510 \fBedonr\fR algorithms.

   1 '\" te
   2 .\" Copyright (c) 2013, 2016 by Delphix. All rights reserved.
   3 .\" Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
   4 .\" Copyright (c) 2014, Joyent, Inc. All rights reserved.
   5 .\" Copyright (c) 2014 Integros [integros.com]
   6 .\" Copyright (c) 2016, Nexenta Systems, Inc. All rights reserved.
   7 .\" The contents of this file are subject to the terms of the Common Development
   8 .\" and Distribution License (the "License").  You may not use this file except
   9 .\" in compliance with the License. You can obtain a copy of the license at
  10 .\" usr/src/OPENSOLARIS.LICENSE or http://www.opensolaris.org/os/licensing.
  11 .\"
  12 .\" See the License for the specific language governing permissions and
  13 .\" limitations under the License. When distributing Covered Code, include this
  14 .\" CDDL HEADER in each file and include the License file at
  15 .\" usr/src/OPENSOLARIS.LICENSE.  If applicable, add the following below this
  16 .\" CDDL HEADER, with the fields enclosed by brackets "[]" replaced with your
  17 .\" own identifying information:
  18 .\" Portions Copyright [yyyy] [name of copyright owner]
  19 .TH ZPOOL-FEATURES 5 "Mar 25, 2016"
  20 .SH NAME
  21 zpool\-features \- ZFS pool feature descriptions
  22 .SH DESCRIPTION
  23 .LP
  24 ZFS pool on\-disk format versions are specified via "features" which replace
  25 the old on\-disk format numbers (the last supported on\-disk format number is
  26 28). To enable a feature on a pool use the \fBupgrade\fR subcommand of the
  27 \fBzpool\fR(1M) command, or set the \fBfeature@\fR\fIfeature_name\fR property
  28 to \fBenabled\fR.
  29 .sp
  30 .LP
  31 The pool format does not affect file system version compatibility or the ability
  32 to send file systems between pools.
  33 .sp
  34 .LP
  35 Since most features can be enabled independently of each other the on\-disk
  36 format of the pool is specified by the set of all features marked as
  37 \fBactive\fR on the pool. If the pool was created by another software version
  38 this set may include unsupported features.
  39 .SS "Identifying features"

 470 .RE
 471 .sp
 472 .ne 2
 473 .na
 474 \fB\fBlarge_blocks\fR\fR
 475 .ad
 476 .RS 4n
 477 .TS
 478 l l .
 479 GUID    org.open-zfs:large_block
 480 READ\-ONLY COMPATIBLE   no
 481 DEPENDENCIES    extensible_dataset
 482 .TE
 483 
 484 The \fBlarge_block\fR feature allows the record size on a dataset to be
 485 set larger than 128KB.
 486 
 487 This feature becomes \fBactive\fR once a \fBrecordsize\fR property has been
 488 set larger than 128KB, and will return to being \fBenabled\fR once all
 489 filesystems that have ever had their recordsize larger than 128KB are destroyed.
 490 
 491 .RE
 492 
 493 .sp
 494 .ne 2
 495 .na
 496 \fB\fBvdev_properties\fR\fR
 497 .ad
 498 .RS 4n
 499 .TS
 500 l l .
 501 GUID    com.nexenta:vdev_properties
 502 READ\-ONLY COMPATIBLE   yes
 503 DEPENDENCIES    none
 504 .TE
 505 
 506 This feature indicates that the pool includes on-disk format changes that
 507 support persistent vdev-specific properties. This feature will be
 508 \fBactive\fR when the first vdev-specific property is set.
 509 
 510 .RE
 511 
 512 .sp
 513 .ne 2
 514 .na
 515 \fB\fBcos_properties\fR\fR
 516 .ad
 517 .RS 4n
 518 .TS
 519 l l .
 520 GUID    com.nexenta:cos_properties
 521 READ\-ONLY COMPATIBLE   yes
 522 DEPENDENCIES    com.nexenta:vdev_properties
 523 .TE
 524 
 525 This feature indicates that the pool includes on-disk format changes that
 526 support persistent Class of Storage (CoS) properties. Such properties can
 527 be associated with a collection of device that belong to a common class
 528 from storage management standpoint. This feature will be
 529 \fBactive\fR when the first CoS property is set.
 530 
 531 .RE
 532 
 533 .sp
 534 .ne 2
 535 .na
 536 \fB\fBmeta_devices\fR\fR
 537 .ad
 538 .RS 4n
 539 .TS
 540 l l .
 541 GUID    com.nexenta:meta_devices
 542 READ\-ONLY COMPATIBLE   yes
 543 DEPENDENCIES    none
 544 .TE
 545 
 546 This feature flag indicates presence of special-vdev in the pool. Special
 547 vdev is used to speed-up read and write operations and can be used to store
 548 ZFS metadata and/or write log (ZIL). In addition, special vdev can function
 549 as a writeback cache (WBC) within the pool, accelerating ZFS writes via
 550 underlying fast media (typically, write-optimized SSD). 
 551 
 552 Note that unlike the first two functions the WBC function is configurable 
 553 on a per-dataset tree basis.
 554 
 555 .RE
 556 
 557 .sp
 558 .ne 2
 559 .na
 560 \fB\fBwbc\fR\fR
 561 .ad
 562 .RS 4n
 563 .TS
 564 l l .
 565 GUID    com.nexenta:wbc
 566 READ\-ONLY COMPATIBLE   no
 567 DEPENDENCIES    com.nexenta:meta_devices
 568 .TE
 569 
 570 When enabled, this feature indicates that the pool supports writeback caching.
 571 The latter can be activated on a specific filesystem (and all its children) or
 572 a volume (zvol) within the pool by setting the corresponding  \fBwbc_mode\fR
 573 property to 'on'. This feature will show up as \fBdisabled\fR if the pool does
 574 not contain special-vdev.
 575 
 576 .RE
 577 
 578 .sp
 579 .ne 2
 580 .na
 581 \fB\fBsha512\fR\fR
 582 .ad
 583 .RS 4n
 584 .TS
 585 l l .
 586 GUID    org.illumos:sha512
 587 READ\-ONLY COMPATIBLE   no
 588 DEPENDENCIES    extensible_dataset
 589 .TE
 590 
 591 This feature enables the use of the SHA-512/256 truncated hash algorithm
 592 (FIPS 180-4) for checksum and dedup. The native 64-bit arithmetic of
 593 SHA-512 provides an approximate 50% performance boost over SHA-256 on
 594 64-bit hardware and is thus a good minimum-change replacement candidate
 595 for systems where hash performance is important, but these systems
 596 cannot for whatever reason utilize the faster \fBskein\fR and
 597 \fBedonr\fR algorithms.