From b25f375dac76b1e4d86b219fb851500744abd168 Mon Sep 17 00:00:00 2001 From: Vladislav Bolkhovitin Date: Wed, 3 Jun 2009 18:57:37 +0000 Subject: [PATCH] Web updates git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@890 d57e44dd-8a1f-0410-8b47-8ef2f437770f --- www/comparison.html | 66 +++++++++++++++++++----------------- www/mc_s.html | 8 ++--- www/scstvsstgt.html | 7 ++-- www/target_qla22xx_23xx.html | 2 +- 4 files changed, 42 insertions(+), 41 deletions(-) diff --git a/www/comparison.html b/www/comparison.html index 7d6068204..1f68ce0dc 100644 --- a/www/comparison.html +++ b/www/comparison.html @@ -43,7 +43,7 @@

Features comparison between Linux SCSI targets

-

As on April 2009

+

As on June 2009

@@ -145,20 +145,22 @@ resized through AENs or Unit Attentions +SCSI requirements 12 +14 + + 15 + 16 @@ -226,14 +228,14 @@ ORDERED commands + 17 @@ -303,13 +305,13 @@ devices +reinstatement 21 - + + 16
+ - (Windows 2003 clustering) + + + +
Safe RESERVE/RELEASE implementation according to -SCSI requirements 12 Safe Safe Not safe Not safe Safe Safe Not safe + + 13 Not safe
Safe implementation of Task Management commands -13 Safe Not safe Not safe Not safe Safe Not safe Not safe Not safe
Support for SCSI task attributes, including ORDERED commands + + -,
data corruption possible - - 21		 -,
data + + 15		 -,
data corruption possible - - 21
Persistent Reservations
@@ -172,7 +174,7 @@ ORDERED commands		 + + -,
data
SCSI MIBs - - - - - 15
Cluster Storage Integration - - - VHACS + + -,
data
SCSI pass-through - 16 + - - Single initiator only, not enforced - 17 + - - Single initiator only, not enforced + 18
Zero-copy data read/write to/from backstorage BLOCKIO, user space FILEIO in O_DIRECT mode, pass-through - 18 + 19 - 8 BLOCKIO BLOCKIO, pass- @@ -276,7 +278,7 @@ devices - Experimental - -
Zero-copy data send/receive Send only - 19 + 20 None 8 Send only Send only - Experimental - - + - - -
Safe implementation of connections and sessions -reinstatement 20 Safe Not safe Not safe Not safe Safe Not safe Not safe Not safe
Safe restart 21 Safe ? Not safe ? Safe restart 22 Safe ? Not safe ?
iSCSI MIBs - - - - - 15
@@ -322,9 +324,8 @@ reinstatement 20 Safe Not s

2. All iSCSI management implemented in user space and actual data transfers in kernel space without user space involved.

3. ISER target driver has long known (since Feb 2008) data corruption problem, which localization hasn't been determined yet and might be - in the STGT core. See - http://lists.berlios.de/pipermail/stgt-devel/2008-February/001367.html and - http://lists.wpkg.org/pipermail/stgt/2009-February/002630.html.

+ in the STGT core. See here and + here.

4. The result "in average" is listed. One target can be better somewhere, another one somewhere else. Although manual tuning of target and system parameters tends the restore the difference listed in the comparison. You can find example measurements here, @@ -362,7 +363,11 @@ reinstatement 20 Safe Not s "Russian roulette with your data" on the VMware community forum by someone working for VMware.

-

13. After a task management command completed and before the corresponding response was sent to the initiator, who sent that task management +

13. The problem in IET + + was confirmed in IET mailing list.

+ +

14. After a task management command completed and before the corresponding response was sent to the initiator, who sent that task management command, all the affected SCSI commands must get into a state, where they can't affect following after the tasks management response commands from this initiator. This is the safe implementation. The unsafe implementation only marks all the affected @@ -372,35 +377,34 @@ reinstatement 20 Safe Not s SCSI command, which initiator will send after it received the task management response thinking that all the aborted commands actually fully aborted. This could lead to a data corruption.

-

14. Both IET and LIO report in INQUIRY command response support for full task management model. But they process ORDERED +

15. Both IET and LIO report in INQUIRY command response support for full task management model. But they process ORDERED commands the same way as SIMPLE commands, i.e. allow free reorder of them before they get executed. That violates SCSI standard and can lead to a data corruption to any application relying on commands order provided by ORDERED attribute.

-

15. The IETF SCSI-MIB (RFC 4455) is not supported by LIO, only proprietary MIBs SBE-SCSI-MIB, SBE-ISCSI-MIB and SBE-IPS-AUTH-MIB are supported.

+

16. The IETF SCSI-MIB (RFC 4455) is not supported by LIO, only proprietary MIBs SBE-SCSI-MIB, SBE-ISCSI-MIB and SBE-IPS-AUTH-MIB are supported.

-

16. SCSI pass-through mode allows to export your local SCSI-capable device. For instance with it you can share your parallel +

17. SCSI pass-through mode allows to export your local SCSI-capable device. For instance with it you can share your parallel SCSI tape or SATA DVD-RW device to your iSCSI network.

-

17. LIO doesn't emulate all the necessary SCSI host functionality to allow to share SCSI devices +

18. LIO doesn't emulate all the necessary SCSI host functionality to allow to share SCSI devices in pass-through mode to several initiators. It can only pass SCSI commands from initiators to SCSI devices and responses back. This is safe only with a single initiator. This limitation - isn't enforced anyhow and LIO doesn't issue no warning about it, so you can quietly corrupt your data. - You can find more technical information about that in - - http://www.mail-archive.com/linux-scsi@vger.kernel.org/msg06911.html

+ isn't enforced anyhow and LIO doesn't issue no warning about it, so an user will not be notified about it + and can quietly corrupt his/her data. You can find more technical information about it + here.

-

18. You can find proposal how to implement zero-copy FILEIO in SCST on the +

19. You can find a proposal how to implement zero-copy FILEIO in SCST on the Contributing page.

-

19. Doesn't need any kernel patch, except in case, when used with user space backend.

+

20. Doesn't need any kernel patch, except in the case, when used with user space backend.

-

20. Connections and sessions reinstatement is, basically, a kind of Task Management command, because it implies commands aborting. +

21. Connections and sessions reinstatement is, basically, a kind of Task Management command, because it implies commands aborting. For instance, open-iscsi uses it as a less intrusive substistute for target reset in eh_target_reset_handler() callback. So, similarly to the safe task management above, a safe implementation of connections and sessions reinstatement must not accept SCSI commands from new connection/session until all the SCSI commands in being reinstated connection/session get into a state, where they can't affect new commands.

-

21. "Safe restart" means that after the iSCSI target restart, all the connected initiators will seamlessly restore all existing before +

22. "Safe restart" means that after the iSCSI target restart, all the connected initiators will seamlessly restore all existing before the restart connections. "Not safe" means that, most likely, the connected initiators will fail to restore existing connections with some errors.

diff --git a/www/mc_s.html b/www/mc_s.html index 0a84bf763..baf268ba7 100644 --- a/www/mc_s.html +++ b/www/mc_s.html @@ -173,7 +173,7 @@ commands get executed, although it would be better for performance to reorder them. As result, MPIO sometimes has better performance, than MC/S, especially in setups, where maximum IOPS number is important. See, for instance, -http://article.gmane.org/gmane.linux.scsi/16311. +here.

When MC/S is better than MPIO

@@ -232,10 +232,8 @@ and backup applications one or both can be true. But on practice:

Simply, MC/S is done on the wrong level. No surprise then that no Open Source OS'es neither support, nor going to implement it. Moreover, when back to 2005 there was an attempt to add MC/S in Linux, it was -rejected. See for more details http://article.gmane.org/gmane.linux.scsi/15769 -and http://article.gmane.org/gmane.linux.scsi/16301. +rejected. See for more details here +and here.

If in future SCSI standards gain possibility to group several I_T nexuses diff --git a/www/scstvsstgt.html b/www/scstvsstgt.html index 1c8c3619d..af8b2c59b 100644 --- a/www/scstvsstgt.html +++ b/www/scstvsstgt.html @@ -49,8 +49,8 @@ found its way to the kernel.

But such architecture has several inherent problems. Among them performance and complexity. - See description for the set of patches, submitted for the first iteration of in-kernel inclusion review and comments - http://lkml.org/lkml/2008/12/10/245

+ See description for the set of patches, submitted for + the first iteration of in-kernel inclusion review and comments in Linux kernel mailing list.

See also the following important discussions:

diff --git a/www/target_qla22xx_23xx.html b/www/target_qla22xx_23xx.html index d4078ff76..a56d4620c 100644 --- a/www/target_qla22xx_23xx.html +++ b/www/target_qla22xx_23xx.html @@ -54,7 +54,7 @@

Target driver for QLogic 22xx/23xx cards

- This is target driver for QLogic 22xx/23xx Fibre Channel cards. It is stable and well tested.

+ This is target driver for QLogic 22xx/23xx (qla2200/qla2300) Fibre Channel cards. It is stable and well tested.

The latest stable version is 1.0.1. Requires Linux kernel version 2.6.16.x or higher and SCST version 1.0.1 or higher.