lio vs stgt
yfceph
4 Posts
November 4, 2016, 9:44 amQuote from yfceph on November 4, 2016, 9:44 amHow you consider lio with stgt.lio with rbd maybe depend on kernel version and every scsi cmd will go through block io layer.Stgt maybe perfect io path in user space with librbd.
How you consider lio with stgt.lio with rbd maybe depend on kernel version and every scsi cmd will go through block io layer.Stgt maybe perfect io path in user space with librbd.
admin
2,930 Posts
November 4, 2016, 12:31 pmQuote from admin on November 4, 2016, 12:31 pmVery valid question. When we started PetaSAN early 2015 we looked at the different options: ISTGT (used in FreeBSD and FreeNAS at the time), SCST,STGT/TGT and LIO. They are all excellent options and it was by no means an easy decision.
You are correct that LIO is more difficult to work with, being all kernel code we have to maintain our patches and merge them with new kernels. But kernel code gives you the best performance. LIO is also the linux standard target and has up to date support for iSCSI Persistent Reservations and VMware VAAI API, i believe it is better than STGT in this area. At one point ( before SUSE Enterprise Storage 2 with iSCSI support was released in Nov 2015 ) we were looking into using LIO tcmu module with a user space backstore using librbd.
Lastly both SUSE and Red Hat are/will use LIO for iSCSI gateways to Ceph.
Very valid question. When we started PetaSAN early 2015 we looked at the different options: ISTGT (used in FreeBSD and FreeNAS at the time), SCST,STGT/TGT and LIO. They are all excellent options and it was by no means an easy decision.
You are correct that LIO is more difficult to work with, being all kernel code we have to maintain our patches and merge them with new kernels. But kernel code gives you the best performance. LIO is also the linux standard target and has up to date support for iSCSI Persistent Reservations and VMware VAAI API, i believe it is better than STGT in this area. At one point ( before SUSE Enterprise Storage 2 with iSCSI support was released in Nov 2015 ) we were looking into using LIO tcmu module with a user space backstore using librbd.
Lastly both SUSE and Red Hat are/will use LIO for iSCSI gateways to Ceph.
lio vs stgt
yfceph
4 Posts
Quote from yfceph on November 4, 2016, 9:44 amHow you consider lio with stgt.lio with rbd maybe depend on kernel version and every scsi cmd will go through block io layer.Stgt maybe perfect io path in user space with librbd.
How you consider lio with stgt.lio with rbd maybe depend on kernel version and every scsi cmd will go through block io layer.Stgt maybe perfect io path in user space with librbd.
admin
2,930 Posts
Quote from admin on November 4, 2016, 12:31 pmVery valid question. When we started PetaSAN early 2015 we looked at the different options: ISTGT (used in FreeBSD and FreeNAS at the time), SCST,STGT/TGT and LIO. They are all excellent options and it was by no means an easy decision.
You are correct that LIO is more difficult to work with, being all kernel code we have to maintain our patches and merge them with new kernels. But kernel code gives you the best performance. LIO is also the linux standard target and has up to date support for iSCSI Persistent Reservations and VMware VAAI API, i believe it is better than STGT in this area. At one point ( before SUSE Enterprise Storage 2 with iSCSI support was released in Nov 2015 ) we were looking into using LIO tcmu module with a user space backstore using librbd.
Lastly both SUSE and Red Hat are/will use LIO for iSCSI gateways to Ceph.
Very valid question. When we started PetaSAN early 2015 we looked at the different options: ISTGT (used in FreeBSD and FreeNAS at the time), SCST,STGT/TGT and LIO. They are all excellent options and it was by no means an easy decision.
You are correct that LIO is more difficult to work with, being all kernel code we have to maintain our patches and merge them with new kernels. But kernel code gives you the best performance. LIO is also the linux standard target and has up to date support for iSCSI Persistent Reservations and VMware VAAI API, i believe it is better than STGT in this area. At one point ( before SUSE Enterprise Storage 2 with iSCSI support was released in Nov 2015 ) we were looking into using LIO tcmu module with a user space backstore using librbd.
Lastly both SUSE and Red Hat are/will use LIO for iSCSI gateways to Ceph.