Problem adding SCSI quirks for a SSD, 4K sector and ZFS

[Steven Hartland]

----- Original Message ----- 
From: "Borja Marcos" <borjam at sarenet.es>
To: <freebsd-scsi at freebsd.org>
Cc: "FreeBSD Filesystems" <freebsd-fs at freebsd.org>
Sent: Thursday, January 24, 2013 9:46 AM
Subject: Problem adding SCSI quirks for a SSD, 4K sector and ZFS


>
> Hello,
>
> Crossposting to FreeBSD-fs, as I am wondering if I have had a problem with ZFS and sector size detection as well.
>
> I am doing tests with an OCZ Vertex 4 connected to a SAS backplane.
>
> < OCZ-VERTEX4 1.5>                 at scbus6 target 22 lun 0 (pass19,da15)
>
> (The blank before "OCZ" really appears there)
>
> pass19: < OCZ-VERTEX4 1.5> Fixed Direct Access SCSI-5 device
> pass19: Serial Number OCZ-1SVG6KZ2YRMSS8E1
> pass19: 3.300MB/s transfers
>
> I am bypassing an "aac" RAID card so that the disks are directly attached to the da driver, instead of relying on the so-called 
> JBOD feature.
>
> I have had a weird problem, with the disk being unresponsive to the REQUEST CAPACITY(16) command. Weird, seems it timeouts.
>
> So, just to complete the tests, I have added a quirk to scsi_da.c. Anyway, I also need the disk to be recognized as a 4K sector 
> drive.
>
> I created a new quirk, called it DA_Q_NO_RC16, and added an  entry to the quirk table, so that these drives are recognized as 4K 
> drives  and the driver doesn't try to send a RC(16) command.
>
> diff scsi_da.c.orig scsi_da.c
> 93c93,94
> < DA_Q_4K = 0x08
> ---
>> DA_Q_4K = 0x08,
>> DA_Q_NO_RC16 = 0x10
> 811a813,817
>> /* OCZ Vertex 4 firmware 1.5 */
>> { T_DIRECT, SIP_MEDIA_FIXED, "", "OCZ-VERTEX4", "*" },
>> /*quirks*/DA_Q_NO_RC16 | DA_Q_4K
>> },
>> {
> 1635,1636c1641,1646
> < /* Predict whether device may support READ CAPACITY(16). */
> < if (SID_ANSI_REV(&cgd->inq_data) >= SCSI_REV_SPC3) {
> ---
>> /*
>> * Predict whether device may support READ CAPACITY(16).
>> * BUT Some disks don't support RC(16) even though they should.
>> */
>> if ((SID_ANSI_REV(&cgd->inq_data) >= SCSI_REV_SPC3)
>> && !(softc->quirks & DA_Q_NO_RC16) ) {
>
>
>
> I think it's working. I haven't seen any more RC(16) errors, and the disk is working fine. Anyway I am not sure I've done it 
> right. After adding the 4K quirk and rebooting, GEOM_PART complained that the partitions weren't aligned to 4K
>
> /var/log/messages.0:Jan 23 16:01:30  kernel: GEOM_PART: partition 1 is not aligned on 4096 bytes
> /var/log/messages.0:Jan 23 16:01:30  kernel: GEOM_PART: partition 2 is not aligned on 4096 bytes
>
> So it seems it works. However, when using the disk for ZFS, it still detects a 512 byte sector size, which is odd.
>
> Jan 23 16:01:30 rasputin kernel: GEOM: new disk da15
> Jan 23 16:01:30 rasputin kernel: da15 at aacp0 bus 0 scbus6 target 22 lun 0
> Jan 23 16:01:30 rasputin kernel: da15: < OCZ-VERTEX4 1.5> Fixed Direct Access SCSI-5 device
> Jan 23 16:01:30 rasputin kernel: da15: Serial Number OCZ-1SVG6KZ2YRMSS8E1
> Jan 23 16:01:30 rasputin kernel: da15: 3.300MB/s transfers
> Jan 23 16:01:30 rasputin kernel: da15: 488386MB (1000215216 512 byte sectors: 255H 63S/T 62260C)
>
>
> diskinfo is returning a sector size of 512 bytes, and a stripesize of 4096. Is this correct? ZFS is still detecting it as a 512 
> byte sector disk.
>
> /dev/da15
> 512         # sectorsize
> 512110190592 # mediasize in bytes (477G)
> 1000215216  # mediasize in sectors
> 4096        # stripesize
> 0           # stripeoffset
> 62260       # Cylinders according to firmware.
> 255         # Heads according to firmware.
> 63          # Sectors according to firmware.
> OCZ-1SVG6KZ2YRMSS8E1 # Disk ident.
>
>
>
> So, to summarize:
>
> If the quirk was working, should diskinfo return a sector size of 512 bytes, or is it correct  to show a "stripesize" of 4096?
>
> Do we have a bug either on ZFS  or the disk drivers? The same experiment on another system (both are 9.1-RELEASE) and a similar 
> drive attached to a SATA controller, also adding a 4K sector quirk for it, defines a stripe size instead of a sector size.

Simple answer is ZFS doesn't understand quirks. The attached patch does
what you're looking for along with a few other things, see notes at
the top for details.

Its not a final version as there's still some discussion about
implementation details but it should do what your looking for.

    Regards
    Steve 


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