On 05/16/2015 01:16 AM, Ancoron Luciferis wrote: > On 05/15/2015 06:54 PM, Michael Christie wrote: >> >> On May 7, 2015, at 7:06 AM, Ancoron Luciferis >> <[email protected]> wrote: >> >>> Hi, >>> >>> I currently have some trouble with LUNs exposed by Synology boxes. >>> >>> As of Linux kernel 3.19, the max_sectors_kb value always is 32767 for >>> any LUN, which results into errors on the Synology target side and >>> reconnects on the Linux initiator side: >>> >> >> >> As you saw, in the newer kernel the block/scsi layer will now send requests >> up to the size the target or initiator say they can handle. In your case, >> because the target is reporting zeros, the scsi layer is only using the >> initiator limit which is that 32K. >> >> It seems there is a bug with lio based targets. In this patch for Qnap >> targets which used lio, we just added a new black list flag so we use the >> old default value because we could not contact the vendor to get more info >> as it is not always as simple as just matching the >> max_hw_sectors/max_sectors on the target side: >> >> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/drivers/scsi?id=35e9a9f93994d7f7d12afa41169c7ba05513721b >> >> You can normally manually override the max sectors setting, but that is >> broken under some conditions. It is fixed with this patch >> >> http://marc.info/?l=linux-scsi&m=142864974021809&w=3 >> >> Could you send me the vendor/product info, so we can add your target to the >> blacklist? >> > > Hi, > > thanx for the info. I currently have the following devices at my > disposal for testing: > > * Synology DS409+ > * Synology DS1813+ > * Synology DS1815+ > > All LUNs created on these devices are identified by the following strings: > > Vendor: SYNOLOGY > Product: iSCSI Storage > Revision: 3.1 > > As there is no reliable way to differentiate the block-level from the > file-level LUNs on the initiator side (at least I can't see any reliable > difference in device identification data), setting max_sectors_kb to 512 > should be a safe value for Synology LUNs (1024 is too much for its > block-level LUNs). >
1024 is actually what we have been using for as long as lio based targets have existed, so it should work fine. Did it fail before? It looks like lio based targets would break up a command that is larger than the max sectors value you were looking at. The issue with really large IOs we are see now seems to be trying to allocate enough resources sometimes. -- You received this message because you are subscribed to the Google Groups "open-iscsi" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/open-iscsi. For more options, visit https://groups.google.com/d/optout.
