Re: ZFS secondarycache on SSD problem on r255173

Hows things looking Vitalij?

----- Original Message ----- 
From: "Vitalij Satanivskij" <satan_at_ukr.net>


> Ok. Just right now system rebooted with you patch.
> 
> Trim enabled again.
> 
> WIll wait some time untile size of used cache grow's.
> 
> 
> Steven Hartland wrote:
> SH> Looking at the l2arc compression code I believe that metadata is always
> SH> compressed with lz4, even if compression is off on all datasets.
> SH> 
> SH> This is backed up by what I'm seeing on my system here as it shows a
> SH> non-zero l2_compress_successes value even though I'm not using
> SH> compression at all.
> SH> 
> SH> I think we we may well need the following patch to set the minblock
> SH> size based on the vdev ashift and not SPA_MINBLOCKSIZE.
> SH> 
> SH> svn diff -x -p sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c
> SH> Index: sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c
> SH> ===================================================================
> SH> --- sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c        (revision 256554)
> SH> +++ sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c        (working copy)
> SH> _at__at_ -5147,7 +5147,7 _at__at_ l2arc_compress_buf(l2arc_buf_hdr_t *l2hdr)
> SH>         len = l2hdr->b_asize;
> SH>         cdata = zio_data_buf_alloc(len);
> SH>         csize = zio_compress_data(ZIO_COMPRESS_LZ4, l2hdr->b_tmp_cdata,
> SH> -           cdata, l2hdr->b_asize, (size_t)SPA_MINBLOCKSIZE);
> SH> +           cdata, l2hdr->b_asize, (size_t)(1ULL << l2hdr->b_dev->l2ad_vdev->vdev_ashift));
> SH> 
> SH>         if (csize == 0) {
> SH>                 /* zero block, indicate that there's nothing to write */
> SH> 
> SH> Could you try this patch on your system Vitalij see if it has any effect
> SH> on the number of l2_cksum_bad / l2_io_error?


================================================
This e.mail is private and confidential between Multiplay (UK) Ltd. and the person or entity to whom it is addressed. In the event of misdirection, the recipient is prohibited from using, copying, printing or otherwise disseminating it or any information contained in it. 

In the event of misdirection, illegible or incomplete transmission please telephone +44 845 868 1337
or return the E.mail to postmaster_at_multiplay.co.uk.